Mechanical wound therapy for sub-atmospheric wound care system

ABSTRACT

A mechanical wound therapy (MWT) system includes a connection for a vacuum source, which is routed through an airtight covering to a porous material positioned over the wound. The porous material may be a tubing network interspaced by a netting material constructed of biologically inert or bioabsorbable material. Alternatively, the porous material may be a layered unified dressing in which layers of mesh, netting or thin perforated film are separated and fixedly attached to functional elements of the dressing (e.g., irrigation tubing) or spacers. The vacuum and irrigation systems may be completely separated. An airtight sealing layer or foldable adhesive sealing layer may seal the dressing and facilitate sealing the dressing to the wound margins. Additional modular devices such as a wound approximating system, positive pressure bladders and adjuvant therapy modules as well as enhanced monitoring technology can be added to synergistically increase the capabilities of each dressing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from, and incorporates byreference in their entireties, both U.S. provisional patent application61/554,080 filed Nov. 1, 2011, and also U.S. provisional patentapplication 61/643,840 filed May 7, 2012.

BACKGROUND

1. Technical Field

Various embodiments of the present invention relate to patient woundcare, and more specifically, to systems and methods of wound coveringsand dressings.

2. Description of Related Art

Since the mid-20th century various types of rudimentary vacuum-assisteddevices have been used to facilitate coverage and closure of openwounds. Conventional vacuum-assisted wound care devices use anon-unified, piecemeal wound filling material sealed with an adhesivefilm, and a vacuum pump that maintains negative pressure on the woundwhile draining the effluent from the wound into a fluid collectioncanister.

There is sometimes a need to modify the wound dressing to provide ashape conforming to the wound. In a common conventional system this isdone with wound filler material, often made of an open-cell reticulatedpolyurethane sponge material or cotton gauze. The sponge wound fillermaterial—often black in color, or otherwise opaque—must be cut to theshape and contour of the wound. This material is not particularly easyto cut to shape, generally resulting in multiple odd shaped pieces ofsponge that need to be held in a piecemeal fashion within the wounduntil an adhesive film can be placed to seal the dressing. The presentinventors recognized drawbacks in using this piecemeal approach. Thesedrawbacks exist for the known conventional wound fillers used innegative pressure wound therapy devices.

Different ways of filling the wound cavity have been attempted for theapplication of negative pressure wound therapy. U.S. Pat. No. 6,752,794to Lockwood (Lockwood '794) describes irrigation and vacuum passagewayscreated as channels in a solid noncompressible non-porous member. (SeeLockwood '794, FIGS. 12 and 35). Lockwood '794 uses separate ports forvacuum and irrigation. However, one of the several limitations of thisdesign is that the vacuum passageway between the wound bed and thedorsally located vacuum port can only occur through the limited numberof perforations placed within the solid noncompressible member and thatwhich traverses around the periphery of the member. Additionally, thecommunication between irrigation source tubing and the dressing memberis explicitly demonstrated with a peripheral/horizontal plane attachmentsite, which is believed to be inherent to the design described in theLockwood '794 patent. This limits the ability to custom cut any portionof the periphery of the member to the dimensions of each wound.Likewise, the irrigation passageways specifically stop short of theperipheral extent of the irrigation member.

There are also drawbacks relating to the vacuum regulation system ofconventional devices. Conventional negative pressure wound treatment(NPWT) devices often make broad reference to not placing the dressing inproximity to vascular structures. However, the conventional systems donot specify what would be a safe distance from these structures. Sinceall portions of the body are “in proximity” to vessels, theseconventional systems provide no means for mitigating the risk ofexsanguination. There have been catastrophic complications, even leadingto patient deaths, related to exsanguination events reported to theFederal Drug Administration (FDA) and Centers for Medicare and MedicaidServices (CMS) for certain conventional NPWT systems.

While use of NPWT has become increasingly widespread in the last twodecades, the technologies available in this field remain narrowlyfocused, and are subject to the aforementioned drawbacks and a number ofother shortcomings. Moreover, the present inventors feel NPWT is not astand-alone concept, but that it is a piece in the overall wound careprocess. The management of open wounds from trauma or disease, with theassistance of NPWT, could benefit from the application of multiple otherfeatures which are not provided by any conventional NPWT system. Onesignificant limitation of current art is the lack of a method forintegrating most or all of the commonly used methods of wound care intoa single mechanical system.

BRIEF SUMMARY

Various embodiments are disclosed that do not require pieces of spongeor freely placed piecemeal fillers. In some embodiments there is no needfor a rigid collection canister. Rather, a malleable bag is used forcollection of the fluids.

Various embodiments disclosed herein are drawn to an integratedmechanical wound therapy (MWT) system. The various embodiments combinedifferent aspects of wound care, which currently operate in a segregatedfashion. Operating in such a segregated manner is often disadvantageousin terms of consistency, efficiency and efficacy of wound care. Further,some elements of modern wound care cannot readily be performed withoutintegration of the component parts into the MWT system. For example,various embodiments of the integrated wound care systems disclosedherein benefit from some or all of the following features: Negativepressure wound therapy; Wound monitoring; Irrigation; Debridement;Delivery of adjuvant therapies (e.g., chemical, biological, mechanical,energy systems); Wound contraction (e.g., controlled woundapproximation/dermatotraction); and/or Edema control (e.g., intermittentpositive-pressure).

The current inventors are the first to describe a unified dressingcapable of providing NPWT. In regards to the novel dressing embodimentsdescribed herein, the term unified is intended to indicate that thedressing elements, which constitute the portions of the overall MWTsystem that cover and seal the wound, along with a portion of thetubing, when tubing is a part of the dressing embodiment as well as anyincorporated functional or adjuvant elements described herein, arepresent as a single composite unit through fabrication and packaging.This description is used to clearly delienate this novel concept of awound dressing capable of providing NPWT from conventional NPWTdressings, which all require some sort of assembly of the dressing atthe time of application. The “one-piece” design described herein affordsa clear clinical advantage over conventional “piece-meal” dressings. Thecurrent inventors are also the first describe a novel form of pulsedirrigation, which can be applied either via positive pressure pumpingaction (mechanical or manual) or by reverse lavage, which is a novelmethod for irrigating and cleansing a wound under a closed dressingsystem. Previous art and devices describe or contain elements of anirrigation system, which are not discrete, but rather joined proximal tothe wound dressing and/or wound surface. This design flaw prohibitslavage irrigation, in which bursts of vacuum and irrigation runsimultaneously or near-simultaneously under the control of theprogrammable electronic vacuum regulator. Conventional art that sharestubing or other forms of flow-path between vacuum (out-flow) andirrigation (in-flow) cannot provide this mode of wound cleansing.Conventional systems typically deliver irrigant to the dorsal surface ofthe dressing and not directly to the wound surface. This design drawbackfurther makes lavage irrigation impossible for conventional devices,which “instill” irrigant to the surface of the dressing not facing thewound, and allow or hope for irrigant to soak through the dressingmaterial to reach the underlying wound. This method only ensures wettingof the wound filler, which does not replicate the elements of irrigationused currently in open surgical procedures. Then at some determined timeinterval later, the instilled irrigant can be suctioned from the sealeddressing/wound. Thus conventional art describes a method of instillingirrigation fluid to a wound bed, which is suboptimal.

In contrast to conventional designs, various embodiments disclosedherein are unique in the delivery of the irrigant and the pathway theirrigant must travel to reach the completely separate vacuum circuit.Irrigant is typically delivered directly to the periphery of the wound.By doing this, the irrigant is forced to travel across the wound surfaceto reach the vacuum portion of the system which is located in thecentral aspect of the dressing. Without direct delivery of the irrigantto the periphery, the irrigant will follow the path of least resistance,which is generally a direct route back to the vacuum source.Additionally, under the reverse pulse lavage mechanism, the drivingforce behind the irrigation is not a positive injecting force, which canallow for pooling and compromise of the airtight seal, instead irrigateis pulled in a controlled fashion by bursts of negative pressure fromthe vacuum circuit. By allowing suction to drive the delivery of theirrigant with short pulses of negative pressure, the irrigant isunlikely to pool and compromise the seal at the periphery of thedressing. The current inventors describe a novel irrigation deliverymethod for ensuring the entire wound is irrigated while also limitingthe potential detrimental effects of allowing irrigant to pool andcompromise the seal.

The current inventors describe a distinctly different compositedressing, that is formed from several elements, which represents anonobvious, useful improvement over the conventional art, in terms ofmanufacturing cost and simplicity of application and use. Further, thereis a clinical benefit over conventional art that describes a channeledsolid member dressing construction, which limits communication betweenthe wound surface and the dorsal vacuum port, leaving interveningportions of the wound surface to be directly apposed/effaced by thesolid portion of the dressing member, as opposed to the currentinventors design, in which the porous dressing maintains dead spacebetween functional elements of the dressing by affixing the functionalelements to mesh or similar material, typically in a layeredconstruction that provides a plethora of flow-paths between the woundsurface and vacuum interface, regardless of whether an irrigationelement is present or absent. These open (dead) spaces are alsoclinically advantageous, as the dead space within the volume of thedressing, is a space into which the dressing can collapse upon itself asthe wound is progressively approximated by additional modules of thisMWT system or under the normal contractile nature of some wounds. Solidmembers that are noncompressible are generally avoided in MWT—woundapproximation. Further, the noncompressible nature of a solid member,may serve to focus excessive and even harmful pressure at a specificpoint of the wound bed, leading to pressure-related tissue injury.

In undulating wound beds the constrained geometric properties of a solidthree-dimensional dressing member serve to limit the ability of thematerial to conform to the random, irregular geometry of the wound bed.The current inventors describe a layered dressing, single layer dressingor unidirectional wound filler based dressing, which overcomes thisdesign constraint, allowing it to be sufficiently thin and pliable tomatch the undulations in wounds. The thinness of the layering/nettingmaterial described herein is limited solely by the material propertiesneeded to maintain the basic MWT design (measurable in tenths ofmillimeters), while the thinness of a solid member design is limited bythe minimally acceptable channel depth needed to ensure unblockedcommunication of wound effluent and the vacuum port and/or irrigationport and wound bed (measured in several millimeters). That less idealdesign imposes a functionally significant third dimension whichsubstantially changes the mechanical properties of the dressing in afashion that is disadvantageous to the application of NPWT andinconsistent with the tenets of MWT.

The irrigation tubing system described herein also overcomes limitationsin the conventional art by using a mesh or similar material to layer thedressing. This layering allows for the functional elements (vacuuminterface, irrigation tubing, accessory tubes, monitors, adjuvanttherapy delivery mechanisms) to be placed and maintained in specificspatial relation to one and another. The elements are affixed to thelayers of the dressing though a process of annealing, weaving or othermechanism of fixation. This controlled geometry ensures the elements arein the intended location to provide therapy. Further, the mesh-layeringor tube-netting technique provides this crucial feature, while stillpreserving free space between the functional elements, so as to notblock flow paths that are blocked by a solid member construction orcoagulable fluid laden sponge-like wound filing material. Further, theirrigation tubing system described herein delivers the irrigant atgravity in-flow pressure or greater directly to the wound surface,typically at the periphery.

The unique configuration of this dressing provides the greatestassurance that all segments of the wound receive directed irrigation andthat the flow path of the irrigant and wound debris it frees is directedfrom peripheral to the central. This later path of cleansing bestreplicates the current best practice for performing open surgicaldebridement/cleansing of wounds, in which the periphery is approachedfirst and the cleansing process progresses centrally from there. Inaddition, the tubing described herein, as opposed to channels or otherincomplete passageways or conduits, provide an enclosed space, thatallows for specified interaction between the dressing and wound. In thetypical embodiment, perforations in the irrigation tubing system areonly placed in the peripheral most extent of the tubing, so that theflow path of irrigant is from the centrally located irrigation centralconnection point, through the nonperforated central portions of theirrigation tubing to the perforated peripheral portions. In addition,the central location of the irrigation central connection point, iscrucial to the customizability of this dressing, as the peripheralportions of the dressing can be cut to size from any margin of thedressing, to match the contours of the wound without impacting theirrigation or vacuum delivery systems.

It is the unique tubular and unified design described herein thatdirects irrigation to the entire wound bed, a feature not found inconventional systems. Under the lavage mode of irrigation, vacuum can beapplied simultaneously. If the irrigant were not released peripherally,then the areas of the wound peripheral to the irrigation delivery pointwould likely not receive irrigant, especially in a lavage mode, as theflow path would be central, not centripetal. The specialized dedicatedirrigation tubing system described herein, not only effectively deliversirrigation fluid to the wound surface, the “smart dressing” system alsoallows the end-user to customize the mode and timing of delivery ofvacuum and irrigation (gravity flow, positive pressure, lavage, reverselavage) to provide an ideal synchronization of vacuum and irrigationmodalities to treat the wound.

The basic MWT dressing is a “smart dressing” in that it activelymonitors the wound and can tailor care via pre-specified or end-usercustom algorithms to most effectively treat specific wounds. The basicMWT dressing incorporates elements of wound care in addition to negativepressure, in a choreographed fashion. MWT and “smart dressing” are twolinked novel concepts among the various innovative embodiments disclosedherein.

Further, the spatial relationship and flow-paths maintained and createdby the layered dressing construct, allows this irrigation to synergizewith the other cleansing elements of the wound dressing, like theabrasive wound facing surface, micro-motion from the positive pressurebladder and adjuvants (such as ultrasonic agitation) all working toloosen/free undesired surface material from the wound that is thenwashed away from the wound surface and removed via the vacuum system,which is located dorsal and centrally to the wound and irrigation systemto set a specific flow path for debrided material away from the woundsurface. The fixation of mesh-layers to functional elements in a“sandwich” fashion with a dorsal most impervious layer, leads to asingle composite dressing that contains all elements of the novelmechanical wound therapy method in a single dressing, that is ready tobe cut to the size of the wound and sealed to the wound margins toaffect a closed system straight from the packaging.

While the MWT concept includes aspects of care that are contained inNPWT system in a segregated manner, these parts are part of an overallintegrated system in the MWT. This integrated treatment of MWT providesbenefits not available using simple NPWT. For example, without MWT'sapproach of integrating these additions into a single system, thedressing typically cannot remain in place on the wound on for prolongedperiods, for example, for periods as long as 48 to 72 hours, or longer.Further, by using MWT the dressing acts to cleanse the wound, therebyreducing the need for additional surgical debridement and/or reducingrisk of infectious complication. Moreover, the dressing in conventionalNPWT systems on its own only minimally, if at all, contributes towardsdirectly reducing the dimensions of the wound, and these conventionaldressing cannot provide wound monitoring. These elements are notattainable in any other fashion than through the integration of thevarious embodiments disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof the specification, illustrate various embodiments of the invention.Together with the general description, the drawings aid in explainingprinciples of the invention.

FIGS. 1A-C depict an exemplary embodiment of the layered dressing;

FIG. 1D depicts the dorsal surface of an exemplary layered basic MWTdressing which has been sealed to the wound;

FIG. 1E depicts the ventral surface of an exemplary layered basic MWTdressing taken from the perspective of the wound;

FIG. 1F depicts a multi-layered dressing with multiple layers of nettingor mesh aligned in varying degrees of orientation;

FIG. 1G depicts aspects of a woven structure;

FIG. 1H depicts an uncoated woven structure;

FIG. 1I depicts a coated woven structure;

FIG. 1J depicts a system where tubing structures designed to allowpassage of fluid or gas are spatially aligned in a specific manner;

FIG. 1K depicts the result of a process in which a single closed celllayer is made into a porous layer;

FIG. 1L depicts embodiments of a multi-layered dressing configured withan abrasive ventral layer;

FIGS. 1M-O depicts various embodiments of a unified dressing withdifferent tubular structures configured to be placed, as a unit,directly over the wound;

FIG. 1P depicts an embodiment with a top sealing layer sealed to thedressing in a central location;

FIG. 1Q depicts an embodiment with an airtight film over top of wholedressing;

FIG. 1R depicts an embodiment of the central suction cavity;

FIG. 1S depicts an embodiment of a multi-flange design for the suctiondelivery to the dressing;

FIGS. 2A-C depict typical geometric arrangements for the irrigationtubing system and/or vacuum tubing system;

FIGS. 3A-B is a block diagram pertaining to the reverse pulse lavagesystem;

FIG. 4 depicts an embodiment of a multi-looped accessory dressingconfigured to be attached to the underside of the standard dressing;

FIGS. 5A-B depicts an embodiment of wound dressings configured to beattached in series;

FIGS. 6A-B depicts an embodiment of a separating system for gas andfluid mixtures;

FIGS. 7A-B depicts an embodiment of a bladder or positive pressuredevice configured for placement over a standard dressing;

FIGS. 8A-B depict an embodiment of an approximating device;

FIGS. 9A-B depict an embodiment of an approximating device;

FIG. 10 depicts a cutaway view of wound interface chamber depictingmultiple vacuum flow paths;

FIGS. 11A-C depict an embodiment with the adhesive covering folded andstored in a package on the dorsal surface of the unified dressingstructure;

FIGS. 12A-C depict embodiments having different textures on the woundfacing surface;

FIGS. 13A-C depict embodiments of vacuum and irrigation tubing systemsfor an MWT dressing;

FIG. 14 depicts an embodiment with an accessory tube;

FIG. 15 depicts an embodiment of a vacuum and/or irrigation tubingsystem configured with netting or thin perforated film disposed betweenthe sections of tubing;

FIG. 16 depicts an embodiment with multiple pressure sensors; and

FIG. 17 depicts a computer system suitable for implementing the variousembodiments.

DETAILED DESCRIPTION

The present inventors recognized that the management of open wounds fromtrauma or disease, with the assistance of NPWT, benefits from theapplication of multiple features of the embodiments disclosed herein.From the time the wound is created it is beneficial if several interimactivities occur prior to the final step in wound care, definitive softtissue management. These interim activities include irrigation anddebridement, minimization of microbial load, monitoring of the wound andsequential approximation of the wound—that is, closing of the wound—tothe extent possible.

Typically, it is recognized that a wound care system cannot actcompletely independent of provider directed wound care. Surgicalirrigation, gross wound decontamination, and debridement will remain thehallmarks of initial wound care in the foreseeable future. However, thepresent inventors recognized a number of improvements that aid in thedevelopment of a robust MWT integrated systems. Various embodimentsdisclosed herein serve to improve patient care from the time an adequateirrigation and debridement of the wound is completed until the wound isready for delayed primary closure, skin graft, or other means ofdefinitive reconstruction.

FIG. 1A depicts a composite “smart dressing” embodiment of the unifiedMWT system. This embodiment demonstrates a layered “smart dressing” withoverlying modular components, including a wound approximating device101, a positive pressure bladder 102, an irrigation accessory port 103,a SAWS MWT dressing 104, a vacuum line 105, a collection canister 106,and a programmable electronic vacuum regulator (EVR) 107. Thesecomponents are described in further detail, in passages throughout thisspecification.

The composite smart dressing serves as a fully integrated wound caresystem that incorporates the benefits of NP WT along with other basictenets of wound care. As such, the composite smart dressing isadvantageous over conventional vacuum assisted wound care relateddevices which fail to make the leap forward from providing part of woundcare to complete wound care. The present inventors developed themechanical wound therapy (MWT) system to aid in all aspects of completewound care. Additionally, the present inventors describe unique andnovel improvements in each element of the MWT system. This nextgeneration concept in wound care incorporates a number of beneficialelements into an integrated system, in which the whole tends to begreater than the sum of the individual parts. The use of the MWT conceptfor treatment of each unique wound begins with a basic MWT dressing,described below. The MWT dressing is configured to have a series ofintegrated modular components fitted upon it. The modularity of thesystem allows the healthcare provider to fine-tune the MWT to eachunique wound and specific patient situation.

The inventors recognized a number of drawbacks in the conventionalapproach of cutting pieces of wound filler material to the shape andcontour of the wound. For example, at the microscopic level, cutting aconventional open cell foam wound filler can lead to the formation ofdangling free ends. Such free ends sometimes adhere to the wound surfaceand remain in the wound. If left in the wound these particles can act asnidi for infection and/or inflammatory response. In addition, thepiecemeal approach of conventional wound dressings allows for thepotential of retaining entire pieces of the wound filler in deep areasof the wound since the wound filler pieces are placed in the wound in amanner free and separate from each other.

Some conventional dressings employ an open-cell foam wound filler havingpores in the foam which facilitate tissue in-growth. This can lead togross retention of sponge particles, pain, bleeding and damage to thewound bed tissue at serial dressing changes, which tend to be morefrequent with conventional systems (<72 hrs) than for wounds treated bythe MWT concept disclosed herein. Likewise, conventional wound screensor fillers that are unnecessarily thick can become congested withcoagulable fluids (e.g., blood, exudate) which act to clog the woundfiller layer in specific regions, or even globally. This can effectivelyblock the transmission of fluids across the coagulated areas. A regionaldressing failure such as this may cause infections and/or poor woundhealing in areas of the wound underlying these clogged areas of thedressing. The above mentioned limitations of conventional piecemealwound dressings and non-ideal wound filling material apply to variousknown implementations of conventional NPWT devices, not solely to thoseusing open-cell foam.

A shared limitation of conventional NPWT art is that wounds are “filled”with nonporous (e.g., silicon members) or porous materials (which canbecome less porous or nonporous through compaction and coagulation) thatoccupy space between the wound bed and functional elements of thedressing, like the vacuum source, irrigation and/or other modalities.This space occupying effect, is unnecessary to the clinical applicationof NPWT and instead limits the efficacy of the conventional art, byrequiring space-occupying material to be placed between the woundsurface and vacuum source or other functional elements. This materialcan become clotted with coagulable wound effluent, blocked by some othermeans, or in some instances, may be an impediment to flow by design(e.g., silicone members with channeled passageways). In this fashion,conventional wound fillers may represent a limitation to the optimalapplication of NPWT and MWT.

The embodiments disclosed herein provide a novel solution that overcomesthis limitation. Elimination of space occupying wound filler, alsoenables another important innovation described herein. Specifically, thewound approximating feature of MWT is facilitated by a basic MWTdressing that can compress/fold on itself as the wound margins areprogressively approximated. The wound filling material disclosed inconventional art, can act to resist this contractive force. The layeredcomposite technique disclosed herein overcomes this limitation.Additionally, the layered structure will allow for structural integrityof the dressing which may be attached to the skin edges to preventmovement of the dressing or even used to prevent skin retraction itself.

Returning to FIG. 1A, this figure depicts an embodiment of a unifiedlayered dressing 100 for application of MWT. Various unified dressingstructure embodiments disclosed herein overcome drawbacks ofconventional piecemeal cut-to-fit wound fillers through improvements inthe structure and design of the wound screen/filler, elements of theirrigation/vacuum delivery and the basic design of the vacuum/irrigationfunctions. The dressing structure of the various embodiments is“unified” inasmuch as its components are fixedly attached together. Theunified dressing structure is configured to be placed over a wound as asingle composite unit with all the components remaining fixedly attachedtogether, rather than being placed on the wound in a piecemeal manner asis done with conventional systems. One of the advantages of this unifieddesign, is that it improves upon a significant drawback of conventionalsystems that use piecemeal cut-to-fit wound fillers, by preventing orreducing the potential for remnants of the dressing to remain in thewound when the dressing is removed. By “fixedly attached” it is meantthat the components are attached together or otherwise connected in amanner sufficient to allow the fixedly attached components to be handledand positioned as a unit. In some embodiments the fixedly attachedcomponents are permanently fixedly attached and may not be disassembledwithout breaking or deforming them. In other embodiments the fixedlyattached components may be disassembled by unscrewing, unsnapping, orotherwise unfastening the mechanical means used to hold them together.

Additional embodiments of the basic MWT dressing will have higherfunctionality incorporating monitoring and other technology. The unifieddesign allows for a simplified, integrated housing for wires (whenwireless technology is not used) that connect wound surface leveltechnology with the programmable electronic vacuum regulator. Thisfeature is exclusive to a unified design, and not reproducible in bycurrent art which call for piecemeal construction of the dressing. Thespecific placement of components at fabrication of the MWT dressingallows for the computation (in the EVR) of spatial information, likeregional leak detection or wound health. Conventional art does notdescribe a similar means for establishing and maintaining specificposition of functional elements within the dressing.

FIGS. 1B-1C depict embodiments of a basic MWT dressing, demonstratinglayered dressings and the elements within this example of a unifiedlayered dressing. FIG. 1B depicts an exemplary embodiment of the layereddressing. FIG. 1C depicts an expanded view of FIG. 1B, showing variouscomponents of the embodiment. The unified layered dressing embodiment ofFIG. 1C includes an irrigation connection tubing 108, which conductsirrigant in an antegrade fashion from the irrigation source (e.g., 1liter IV bag or fluid pump) to the dressing and wound surface. Theirrigation connection tubing 108 connects the irrigation source to thedorsal surface of the dressing at the tubing connection point. A vacuumconnection tubing 109 conducts wound effluent retrograde from the woundto a collection canister (e.g., the collection canister 106 of FIG. 1A).The vacuum connection tubing 109 connects the dressing (at the dorsalsurface, via the tubing connection point) and the collection canister. Awound pressure sensor cable 110 may be implemented as an insulated,medical grade wire that connects the wound pressure sensor 119 which islocated at or near the surface of the wound to the electronic vacuumregulator, where the information is interpreted, integrated anddisplayable on a display screen. The wound pressure sensor 119 providesdirect measurement of the therapeutic negative pressure reaching thewound surface, as opposed to indirect pressure measurements obtainedmore distal (e.g. farther retrograde along the vacuum tubing system fromthe wound surface) from the wound surface in conventional systems.

With regards to size, the tubing described herein for the dressingembodiments may be approximately 1-3 mm in inner diameter and 3-5 mm inouter diameter. The mesh layers typically allow for openings from 1-5 mmin width. The tubing is fabricated from a soft, pliable biologicallyinert material. The depth or thickness of each layer of the layeringmaterial in the various dressing embodiments is typically 0.5 to 1.5 minin thickness. Therefore, a layered dressing with a tubing system (e.g.irrigation tubing system described herein) incorporated is roughly 3-10mm in depth or thickness.

The size (or area) and shape (e.g. circular, elliptical . . . ) of thedressing can vary based on the function or location of use. In generalthe dressing will be larger in size than the wound it is intended totreat, allowing it to be trimmed to size to match the unique contours ofthe wound. The dressing can be packaged in different sizes such as large(e.g. 12 inches in long axis or diameter), medium (e.g. 6 inches) andsmall (e.g. 3 inches). Dressing size and shape options are numerous, asspecial dressings can be designed for specific uses, such as afasciotomy performed for acute compartment syndrome in which thedressing is more elliptical (e.g. 12 inches×6 inches).

The embodiments depicted in FIGS. 1A-C may feature one or more layers ofpliable layering material such as the layer 113, a dorsal most sealinglayer 111 (sometimes called a cover component or covering layer), whichmay have an apron-like extension 112 beyond the dimensions of thelayered dressing, a ventral layer 117, a vacuum connection tubing 109,irrigation connection tubing 108, an accessory port 123 may be presentin the irrigation tubing 108 or vacuum connection tubing 109. Theaccessory port 123 can be directly accessed, for example, via a Luerlock syringe. The accessory port 123 can be used to directly inputsmaller volumes of irrigant under manual control. A typical use is forthe delivery of medicinal or antiseptic irrigation fluids.

FIGS. 1B-C depict the accessory port 123 (sometimes called a provideraccess port) configured within irrigation connection tubing 108. In asimilar fashion, in some embodiments an accessory vacuum port 108 may bemay be configured within the vacuum connection tubing 109 to allowsampling of the wound effluent and/or a means for clearing a blockagefrom the vacuum connection tubing 109 or its tubing connection point.The accessory port 123 along the irrigation system may be present insome embodiments of the device which allows the provider to directlyinfuse irrigant onto the wound, with the vacuum source on or off at thetime of infusion. Similarly a vacuum access port can be constructed inthe vacuum connection tubing, to allow sampling of the wound effluent.Moreover, the irrigation therapy of various MWT embodiments can beimplemented in the patient's hospital bed, in an out-patient setting, orother environments conducive to patient Care.

An airtight sealing layer 111 (sometimes called a cover component orcovering layer) is typically affixed to or constitutes the dorsal mostlayer of a layered dressing. This layer is composed of airtightmaterial, such as plastic film. It may be a layer of material, or anairtight material that is sprayed or otherwise applied onto theremaining dressing. The application of this layer typically occurs atmanufacturing. In some embodiments an additional thin flexible adhesivelayer may be affixed to the outside of the airtight sealing layer,conforming to its shape. Since such an additional layer is added to thesealing layer 111 and conforms to its shape, the airtight sealing layer111 is still considered the dorsal most layer of the dressing assembly.The sealing layer 111 can be fixedly attached across the entire dorsalsurface of the dressing, attached only in certain points, or it may befree from attachments to the dorsal surface of the remaining layereddressing aside from a central connection to the tubing connection point.The “dorsal” surface is the surface furthest away from the wound. Inembodiments in which the sealing layer 111 is not fixedly attached tothe remaining layered dressing through fabrication, an adhesive can beplaced with peel-away paper backing on the ventral surface of thesealing layer 111. The “ventral” surface is the surface facing thewound. This allows for the sealing layer 111 to be sealed to theremaining dressing at the time of placement into the wound orimmediately after or prior. Sealing layers in this embodiment can becompletely free of the dressing or connected centrally to the tubingconnection point. For those implementations that are completely free ofthe dressing, the sealing layer 111 takes on properties and functionssimilar to an adhesive sealing sheet. In some embodiments, a dorsalsealing layer is permanently affixed (e.g. a spray on coating similar toFlex Seal™) to the dorsal most surface of the layered dressing,typically at fabrication, upon which an additional sealing layer with orwithout central connection to the tubing connection point can bepresent. The advantage of this embodiment is that an immediate airtight,fluid tight sealing layer is present on the unified layered dressing atapplication to the wound, to reduce or eliminate wetting of the dorsalsurface of the dressing and thereby facilitate good removable fixationof the non-affixed sealing layer (e.g. the more dorsal airtight sealinglayer in this embodiment) to the dressing and possibly adjacent skinmargins (e.g. the apron embodiment described below).

An apron 112 can be provided around the outside edge of sealing layer111. In some embodiments the apron 112 is a lateral extension of thesealing layer 112, while in other embodiments the apron 112 overlaps thesealing layer 112. Other embodiments are apronless. As depicted in FIGS.1B-C the apron 112 is an extension of the sealing (dorsal most) layer111 beyond the dimensions of the remaining layers of the layereddressing. The apron 112 is typically composed of the same material asthe sealing layer. In typical embodiments the sealing layer is a thinplastic film, and the apron is an extension of this film beyond theborders of the remaining layered dressing. The apron 112 can have anadhesive with peel-away paper backing on the ventral surface or it maybe adhesive free. In embodiments where there is an adhesive on the apron112, the apron 112 removably affixes itself, and thereby the dressing towhich it is integrally connected, to the skin at the margins of thewound. The durability of the attachment—that is, the strength of thebond with which it is affixed—may be enhanced with placement ofadditional adhesive sealing sheets or agents. In embodiments withoutadhesive on the ventral surface of the apron 112, a tacky, weak adhesivesubstance, similar to Post-It Note™ adhesive can be present on thedorsal surface, with or without peel-away paper backing in place. A“weak adhesive”, sometimes called a “semi-adhesive,” is tacky enough tosupplement adhesion of adhesive sealing sheets between the dressing andthe patient's skin. This serves as a means for enhancing adhesionbetween the adhesive sealing sheets and the dressing and the patient'sskin. The result of this effect is to create an airtight sealed wound,as well as to support NPWT and the other functions conducted under MWT.

Various embodiments feature a vacuum interface chamber 121(Alternatively, in embodiments in which the vacuum interface has noventral floor, this component may be termed the Vacuum InterfaceFlange). The vacuum interface chamber 121 is the point that connects thevacuum connection tubing from the regulated vacuum source to the sealeddressing. In this way, the wound fluid communicates from the sealedportion of the wound through the vacuum interface chamber and ultimatelyto the collection canister via the vacuum connection tubing. The vacuuminterface chamber 121 is typically made from a soft medical gradeplastic (e.g. Silastic) that encloses a specified volume of space withina predetermined height and circumference of the plastic walls, e.g., 2cc to 50 cc. The end result is a closed cell with one or more accessports and perforations. In at least one embodiment there is one mainport on the dorsal surface (the single perforation in the dorsal surfaceof the chamber), which is the tubing connection point for the vacuumcircuit. There are typically a number of perforations in the vacuuminterface chamber 121 on the ventral (wound facing) surface andsometimes on the side surfaces, as well.

The tubing connection point may be configured as part of a vacuuminterface chamber 121 where it can have a one-way valve that preventsback-flow of wound effluent. Thus, in this embodiment wound effluent canonly progress retrograde from the wound once it cross the one-way valvein the tubing connection point and enters the vacuum connection tubing.The internal space of the vacuum interface chamber 121 is keptpatent—that is, open to afford free passage—even under activeapplication of negative pressure to the chamber 121 by its construction.This may be achieved by providing a wall thickness and materialproperties that prevent collapse of the chamber 121 under thetherapeutic range of negative pressure (e.g., 0 to −250 mmHg) or by theplacement of internal risers that prevent collapse. The overallappearance of the vacuum interface chamber 121 may be analogous to thatof a shower head, with one main dorsal input and a multitude offlowpaths on the contralateral surface. This serves to better distributethe negative pressure to the entire wound. The multitude of perforationsmeans that blockage of one or several of the perforations does notcompletely block fluidic connection between the wound and the vacuumconnection tubing/vacuum source. This is a significant advantage overconventional systems that have a single primary flow path by which thevacuum circuit communicates with the sealed wound, which when block bysaturated/coagulated wound filler or other wound-related material,renders the conventional system non-functional. The vacuum connectiontubing 109 is typically in fluidic communication with a collectioncanister (e.g., collection canister 106 of FIG. 1A). As such, the vacuumconnection tubing 109 is configured so that fluids, either liquid orgas, can flow to the collection canister 106. The connection point forthe vacuum connection tubing 109 is generally implemented on the vacuuminterface chamber 121, or flange.

Layer 113 of FIG. 1C is an example of the layering material used invarious embodiments. The ventral layer 117 may be constructed from thesame material as layer 113, or from a different material, depending uponthe requirements of the embodiment. Biologically inert materials such asplastic or a synthetic polymer can be used. Alternatively, the layer mayhave a central core material that is coated with a plastic or polymerfilm to provide specific properties, which may include non-stick,abrasive and cohesive properties. The cohesive property serves to linkthe central core fibers, to prevent or reduce fraying when the layer iscut to size. The thickness of the layers typically is in the range of0.5 mm to 3 mm. The layer 113 may be composed of mesh, netting and/orthin perforated film. In many embodiments—for example, unified layereddressing embodiment—the layering material of the layer 113 is fixedlyattached to the other components of the dressing structure. For example,the layer 113 may be fixedly attached centrally through manufacture tothe vacuum interface chamber 121 (or flange). The mesh or netting layer113, or other layers in the assembly, may be configured to maintain thespatial relationship of the other dressing components. In someembodiments the mesh layer (e.g., layer 113) may be permanently affixedto the other functional elements of the dressing assembly. Dependingupon the implementation, the layer 113 may either be fixedly attached,or not fixedly attached, to the overlying sealing layer 112. Theoverlying sealing layer 112 is typically fixedly attached to theunderlying dorsal surface of functional elements (e.g., irrigationtubing system) and/or spacers, either by direct attachment or byattachment via another element such as the vacuum interface chamber 121and/or a dorsal layer of the layering material. The layer 113 is one ofthe basic elements of the layered dressing assembly.

The mesh, netting and/or thin perforated film layer of the various layer113 are generally constructed from a pliable material that may becovered with a sealing or bonding material. The construction of thislayer material is specified to aid in eliminating the potential forfraying or dangling free ends which can allow dressing material toincidentally be left in the wound bed at dressing changes—a drawback ofconventional systems that could propagate infection or inflammation andlead to less favorable wound healing.

Typically, the layers of the layered dressing assembly are affixedtogether so they can be applied over a wound as a single unit. Invarious embodiments, a layer—e.g., the layer 113—need not be directlyattached to the next most ventral layer, but rather may be affixedindirectly through shared fixed connections to the functional elementsand/or spacers between that layer and the next. In these embodiments oneor more passageways may be formed by layering flat sheets of mesh,netting or thin perforated film, all of which are pliable material withmultiple open spaces or perforations of homogenous or heterogeneousarea, that are interspaced with functional elements of the MWT system orspacers.

In FIGS. 1B-C irrigation tubing layer 115 is an example of a geometricarrangement of the irrigation tubing system. The configuration ofirrigation tubing layer 115 depicted in FIGS. 1B-C has a spiderweb-likeappearance, containing both radial arms and horizontal traversingconnectors. In other embodiments, there are only radial arms. In manyembodiments the irrigation tubing system has a central connection pointto all irrigation tubes that communicates to the wound surface andultimately connects to the irrigation source. This occurs through awound-side irrigation connection tubing. This tube connects from thecentral connection point of the irrigation tubing system to the tubingconnection point for the irrigation circuit at the dorsal surface of theunified dressing, where it connects to the irrigation connection tubing,as described for irrigation connection tubing 108 above. The irrigationtubing layer 115 typically is devoid of perforations for the majority ofits initial flow-path length from the central connection point outward.At a specific, more peripheral length (e.g., 3 cm from the centralconnection point)—which may vary from prefabricated dressing size todressing size (e.g. small size dressing versus large sizedressing)—perforations in the ventral and lateral surfaces of the tubes,but not the dorsal surface, typically of a diameter equivalent to theinner diameter of the irrigation tubing system tubes occur. In at leastone embodiment there are no perforations along the length of the tubes.Instead, the distal ends of the tubes are open, to allow irrigant toflow directly to the periphery of the wound. The tubing system may becomposed of a soft, pliable medical grade plastic and has materialproperties that most closely resemble those of closed suction drainagetubes used currently (e.g., Jackson Pratt 7-French round drain). Due tothe central connection point and radial orientation of the tubingsystem, the periphery of the irrigation tubing layer 115 can be cut atany point, without disturbing flow across the entire irrigation tubingsystem. This allows the system and the dressing in which it is fixedlycontained to be custom cut to fit the shape of the wound being treated.

Ventral layer 117 is the layer that is most ventral, that is, closest tothe wound. Ventral layer 117 is typically another layer composed ofmesh, netting and/or thin perforated film layering material. Thisspecific layer typically has special qualities as it is the ventral-mostlayer, and therefore the layer directly apposed to the wound. In someembodiments the ventral side of the ventral layer 117 is configured tohave an abrasive finish or surface. The abrasive surface works inconjunction with other elements of the MWT system to producemicro-abrasion and micro-debridement at the wound surface. In otherspecialized embodiments, the ventral surface of ventral layer 117 may beconfigured to have a very slick (low coefficient of friction, nonstick)surface which can be made devoid of pores or other points of attachmentfor microbes, especially those most likely to form bio-films. Thisembodiment tends to reduce adhesion of the dressing to the underlyingtissues, ideal for when the dressing is placed over skin grafts or othertenuous tissues, but it can generally be used in any type of wound. Likethe next more dorsal layering material, the ventral-most layer isfixedly attached to the functional elements and/or spacers between them,at the ventral surface of these elements. It is typically not directlyattached to the next more dorsal layering material.

The wound pressure sensor 119 is a negative pressure sensor positionedto sit at or near the wound surface. The wound pressure sensor 119 istypically affixed to the ventral, central surface of ventral layer 117.In some embodiments, the wound pressure sensor may be excluded. In otherembodiments, described below, there are multiple wound pressure sensors.

FIG. 1D depicts the dorsal surface of an exemplary layered basic MWTdressing which has been sealed to the wound. The tubing connection pointis seen centrally with the vacuum and irrigation connection tubing andthe wound pressure sensor cable seen entering this connection point andthe underlying sealed dressing.

FIG. 1E depicts the ventral surface of an exemplary unified layereddressing embodiment, which can also be referred to as a basic MWTdressing. The view of FIG. 1E is taken from the perspective of the woundlooking outward, from underneath the dressing. The ventral facingperforations in the irrigation tubing system are seen in the spider-webembodiment of the irrigation tubing system. This tubing system 133 and137 sits affixed to the ventral most layering material. The centralconnection point 139 is the central point at which the radial tubes 137of the irrigation tubing system come together. It typically does nothave perforations. In embodiments with a wound pressure sensor, it istypically positioned directly ventral to or inherent to the ventralsurface of the central connection point of the irrigation tubing system.The hatched area 135 at the periphery, represents the ventral surface ofthe apron, which may or may not have adhesive.

The embodiments of FIGS. 1A-E have no wound filler per se, as that termis used today in regards to conventional systems with bits of sponge,gauze or nonporous dressing elements serving as wound filling materialthat are cut to fit the shape of the wound. Instead, the presentembodiments feature layers of netting, mesh or thin perforated filmconfigured, either with or without tubing systems. The term “mesh” inthis context is intended to mean a screen-like material made ofinterwoven strands, e.g., metal strands, fiber strands, plastic strands,strands of other synthetic materials, or the like. “Netting” is amaterial with holes, or spaces, that allow fluids and gasses to passthrough the netting. The term “netting” is a broader term than the termmesh. Netting in the present context encompasses the term mesh—that is,all types of mesh materials are netting, but certain types of nettingmaterials are not considered meshes.

The term perforated film describes a material, typically having aconstant thickness, which is very thin, typically 1-3 mm or less. Atproduction of the thin perforated film, through casting, extrusion,stamping or other mode of fabrication, multiple perforations are made inthe film that can be of the same or varying diameter and density, forexample, as discussed above in conjunction with FIG. 1K. Inert materialssuch as plastic or a synthetic polymer can be used. In some embodiments,a textured surface can be fabricated into the ventral surface of thethin perforated film intended to be used as a ventral layer for alayered dressing embodiment or as the film used in a single layereddressing embodiment. This can be an abrasive texture for someindications and in other embodiments it can be very smooth or non-stick.Functional elements of the unified dressing pass above or below theperforated film, but typically not within the film. By contrast, incertain embodiments of the dressing using a mesh or netting layeringmaterial, the functional elements (e.g., irrigation tubing system 115)can be woven or otherwise incorporated into the mesh/netting material atfabrication.

To create depth, the layering of the unified layered dressing embodimentcan be repeated multiple times as needed. While the ventral and dorsallayers most commonly have unique properties, the layering material usedto construct central layers of a multi-layered dressing is typicallyuniform. In these multi-layered embodiments functional elements, such asthe irrigation tubing system, are nonremovably affixed throughfabrication to the layering material ventral and dorsal to thefunctional element. In multi-layered dressings, with a limited number offunctional elements (e.g. only one tubing system) the intervening layerscan be separated by plastic spacers. This pattern of layering materialseparated by functional elements or spacers can be repeated as manytimes as needed to created an intended final thickness and/orfunctionality of the dressing. In some embodiments supporting theadjuvant medical therapy or advanced monitoring modules describedherein, vertical or multi-layer perforations or other means ofalteration to the layered dressing construction can exist that forinstance house elements of the adjuvant medical therapy module (e.g.ultrasound transducer) or permit passage of a device from the dorsalsurface into a deeper (more ventral) layer of the dressing or all theway to the wound bed, while still maintaining an airtight seal over thewound.

FIG. 1F depicts an embodiment with multiple single layers 125 ofnetting, mesh or thin perforated film. These layers 125 are oriented indifferent manners to allow a series of channels that create amulti-layered dressing depicted on the right. By alternating theorientation of the layers 125 (e.g., rotating 45 degrees, as depicted,or by any amount more or less such as 60 degrees, 30 degrees, 15degrees) the channels remain open to fluid and gas but are not straightchannels that encourage deep tissue ingrowth. Additionally, the layerscan be oriented in such a way that the holes do not line up perfectly ontop of each other, thus reducing the size of the straight pathway in thevertical direction or even requiring fluid or gas to travel in a zigzagpathway to travel through the dressing in a vertical manner. The finalproduct on the right can be either layered without permanent fixation sothey can be separated easily or they can be permanently fixed so theproduct is a single composite structure made up of multiple layers.

By having multiple layers as well as holes in the netting, mesh or thinperforated film, fluid or gas can pass through the dressing along twoaxes. In this figure the fluid or gas can pass in a horizontal fashionbetween layers as well as the vertical axis through the holes or openspaces within the layering material. This layered structure facilitatesfluid or gas passage without restriction through the structure in twodifferent directions (horizontal and vertical).

FIG. 1G depicts a woven structure in which the ends 127 of the mesh havebeen cut. In various embodiments the layering material will be a wovenas shown in FIG. 1G (or in some instances, non-woven) mesh that isconstructed so as to eliminate or substantially prevent fraying,unraveling, or other events. This property will prevent dressingmaterial from being retained in the wound at dressing change. Inertmaterials such as plastic or a synthetic polymer can be used.Alternatively, the woven layer may be a central fiber of some type thatis coated with a plastic or polymer to prevent free particles whencutting to size. The thickness of the layers may be from 0.5 mm to 3 mmof depth. If the woven structure is not coated or sealed, the cut ends127 allow for the woven structure to unravel or fray. It also allows forfree ends to be created in the woven structure at corners or curves.These small fragments at a cut edge sometimes become dislodged from thewoven structure in a wound dressing model and remain in the wound.Nonideal woven structure or open cell structure facilitates residualmaterial being left in the wound by the dressing which can lead toinflammatory responses or nidi for infection.

FIG. 1H depicts an uncoated woven structure 129. This structure is madeup of multiple strands that are woven together to create a mesh typedesign. This design, if untreated, may produce small pieces or particlesthat are created when the woven material is cut, as shown on the left.Therefore, the application of a coating or bonding agent, as shown inthe embodiment of FIG. 1I, is used to help prevent the creation of freepieces at the cut edge. By applying a coating to the woven material, thecoating can bond all the stands into a single structure. This coatingtends to prevent or reduce unraveling or fraying. The bonding or coatingagent can provide a structural property that is not easily sheered toprevent the unwanted tearing of the layering material. To this end,biologically well-tolerated/inert or antimicrobial active coatings maybe applied to commercially available mesh during the manufacturingprocess to prevent fraying, as a bonding or sealing layer. The coatingmay consist of, but is not limited to, pliable coating materials such asplastic, rubber, latex or medicinal preparations. Alternatively, thinpliable films may be used of specified thickness, perforation diameterand density as the layering material for the unified layered dressing.In the various embodiments of the layered dressing, the netting, mesh orthin perforated film layering material are configured to preventunraveling by this or other means. This aids in preventing theincidental release of dressing materials that could be retainedaccidentally in the wound bed at dressing change.

Unintended retention of dressing material in the wound bed is a knowndrawback of current art. The novel layered dressing described hereinovercomes this drawback by the specified construction of the layeringmaterial. The layering material is composed of matter possessingsufficient tensile strength to not break and/or release from thedressing proper under the conditions of normal use. In some cases thelayering material is covered by a permanent sealing, coating or bondingfilm that prevents unraveling or otherwise releasing material from thedressing into the wound. Some embodiments feature a film that hasanti-microbial properties through surface release ofantibiotic/antiseptic agents and/or through material properties. Onesuch material property is a surface that has ultra-high smoothness,devoid or limited in sites that support attachment of microbes. Thisaspect of the layering material aids in preventing or reducing theproduction of biofilms on the dressing. Further, the ultra-smoothsurface increases the ease of release of the dressing from the woundsurface at dressing changes, which reduces pain, bleeding and wound bedtissue trauma that occur with less ideal dressing materials used inconventional systems.

Various embodiments involve an all-in-one unified design, which is asingle complete dressing that only needs to be cut to size and sealed tothe wound margins with adhesive strips/film. Thus, in such embodimentsthe entire dressing is one single unit. This differs from theconventional art in which discrete layers or parts of dressing materialand components are independently applied sequentially to create thefinal dressing. In addition to a single-unit design as opposed to apiecemeal design, some of the various embodiments disclosed hereinfurther overcome the potential danger of retained gross fragments of thedressing material inherent to conventional systems by applyingradio-opaque paint/material to key features of the dressing, like thetubing or certain areas of the netting. This radio-opaque paint/materialcan be applied such that incremental segmentation of known lengths(e.g., 1 cm markings) exists, that can be used to measure dimensions andto indicate whether tubing has been left in the wound. In someembodiments radio opaque markers are integrated in the various dressingcomponents—that is, placed within the dressing components or otherwiseattached to the dressing components—to allow them to be identified incase there is concern for retained dressing material in a wound.Therefore, in the undesirable situation in which dressing material isretained, use of these various embodiments generally enables retainedportions of the dressing to be detected by simple fluoroscopy,radiography or possibly CT scan.

This next generation NPWT dressing concept marks an improvement over theconventional NPWT wound-filler based dressing types. The layeringmaterial—e.g., layers 113-117 of FIGS. 1B-C—can serve multiplefunctions. For example, two such functions may be to serve as thesubstrate that provides form to the dressing and a fixation point tomaintain specified spatial relationships between functional elements ofthe dressing. Secondly, the mesh, netting and/or thin perforated filmprovide a multitude of flow-paths for suction and irrigant. By theconstruction of this layering material and its placement in thecomposite dressing, interspaced by functional elements of the dressingand/or spacers, flow-paths are created in the vertical and horizontalplane, as shown in FIG. 1F, thus overcoming drawbacks of conventionaldressings, in which flow paths are limited in number and random inpattern, both of which may increase the chance that segments of thewound filler develop blocked flow-paths.

Additionally, the dressing's inherent structural integrity allows thedressing to be attached to the skin edges and apply a force to the wounditself that tends to resist the wound's tendency to expand. It alsoallows for maintenance of position of the dressing and the containedfunctional elements within the dressing (e.g., irrigant tubing, pressuremonitor, etc) over the wound.

A biodegradable layer may be used to in some embodiments to interfacewith the wound surface and prevent complications due to foreign matterbeing left behind. Possible materials to use are but not limited toPolyhydroxyalkanoate (PHA), Polylactic acid) (PLA), Polycaprolactone(PCL), Polyesteramide (PEA), Aromatic copolyesters (PBAT . . . ),Aliphatic copolyesters (PBSA . . . ), or Polyglycolide or Polyglycolicacid (PGA). The use of a biodegradable ventral layer can aid in avoidingtearing or otherwise disturbing a partially healed wound when thedressing structure is removed. When such a dressing is removed, thebiodegradable layer can be snipped away at the edges or be expected tospontaneously release from the dressing proper, as hydrolysis or otherbiological or chemical effects occurring over the duration of wear ofthe dressing have weakened the integrity of the layer and/or itsfixation to the remaining portions of the unified dressing. Under thisembodiment, if part of the biodegradable layer (e.g., the ventral mostlayer) is left behind, it harmlessly absorbs into the patient's body. Insome embodiments, this bioabsorbable layering material can be used asthe layering material for all layers in the unified dressing.

FIG. 1J depicts an expanded view 150 of an embodiment with tubingstructures designed to allow passage of fluid or gas are spatiallyaligned in a specific manner. Once the alignment of the tubing system155 is set, the spatial alignment is maintained by the netting, mesh orthin perforated film, as shown in 160 of FIG. 1J. In this diagram, thelayer 151 above and the layer 153 below the tubing system 155 maintainits position. An alternate embodiment is configured with only one layer,e.g., only one layer either above, below or between (e.g. in the sameplane as) the tubing system 155. This ability of maintaining alignmentcan be facilitated by having structural integrity of the layers 151 and153 and some minimal tensile strength to prevent movement of the tubingsystem 155.

FIG. 1K depicts the result of a process in which a single layer of thinfilm 163 is made into a porous layer. This process can be accomplishedthrough multiple manners. In the example depicted in the figure thepores or holes are created using a cutting or punch process, forexample, using a tool such as a group of cutting tubes 167. In this waypore or holes are created through a single solid thin film to create athin perforated film layer 165. This process aids in preventing freeedges or pieces from being created. This manufacturing process orstructure may be used to eliminate unraveling or fraying that istypically encountered with some woven or multi-strand mesh or nettingstructures. The ultimate goal is to eliminate the concern for leavingsmall pieces of loose strands or pieces within a wound bed.

FIG. 1L depicts embodiments of a multi-layered dressing configured withan abrasive ventral layer 157. This layer 157 allows formicro-debridement of the wound to assist in the removal of dead tissuefrom the wound surface. This abrasive surface 157 can move across thewound by any or all of the following effects: the push/pull motioninduced by cyclic inflation/deflation of the positive pressure bladder,sheer motion from the dorsal surface of the unified dressing rubbingagainst the environment and/or from the muscle in or immediately deep tothe wound bed contracting. The abrasive quality of this layer can bemanufactured by several different means. For example, one such manner ofimplementing the abrasive includes the creation of elevations (e.g. <1to 5 mm in height and separation. Alternatively, an abrasive coat orapplication can be applied to the wound facing surface of the layeringmaterial which would randomly alter the thickness of the wound facinglayer. This abrasive coat 157 creates a micro-abrasive wound facingsurface to facilitate wound cleansing.

Some embodiments feature layers of biologically inert polymer netting,mesh or thin perforated film, interposed between which are functionalelements of the MWT dressing, or spacers. A “biologically inertmaterial” does not decompose in a wound. This design controls spatialorientation of these functional elements to effectively apply the MWTconcept, while maintaining flow-paths between the vacuum and irrigationsource and the surface of the wound. The ability to specify the locationof specific functional elements of the unified dressing is a novel anduseful improvement inherent to this design, as specific spatialresolution is required to support advanced “smart” features of the MWTsystem (e.g. forms of leak site detection, wound surface monitoring,selective site delivery of irrigant . . . ). Piece-meal conventionalsystems cannot provide this same specified spatial resolution. Further,the layering material reduces or eliminates tissue in-growth whichcomplicates conventional systems. Another of the several advantages thecontrolled spatial relationship between elements in the unified layereddressing, is that it tends to minimize, or controls in a way favorableto the clinical intent, the space-occupying effect of the dressing tofacilitate wound contraction.

FIGS. 1M-O depicts various embodiments of a unified dressing withdifferent tubular structures configured to be placed, as a unit,directly over the wound itself rather than using the wound fillingmaterials of conventional systems or the layer dressing disclosed forthe embodiments depicted in FIGS. 1B-C. While this single layer dressingembodiments do not require wound filling materials, in certain clinicalindications the single layer dressing can be placed over wound fillingmaterials (e.g. sponge, gauze or other). In these cases, the woundfilling material can be placed piece-meal or it can be permanentlyaffixed to the single layer dressing through fabrication to form aunified composite dressing. In the embodiments of FIGS. 1M-O the tubingsystem and wound netting, mesh or thin perforated film are integratedinto a single unified layer by affixing the netting, mesh or thinperforated film to the tubing or weaving or otherwise fabricating thetubing into the netting, mesh or thin perforated film. The tubularsystem provides the dedicated flow path(s) for vacuum, or for vacuum andirrigation. When the tubular system is used to convey vacuum andirrigation, the ventral (closest to the wound) portions of the tubingmay be shared or remain separated out to the wound surface.

This design differs from previous designs (Shuler Published U.S. PatentApplication Number: US2011/0054283A1) in that the tubing directsirrigant to the periphery of the dressing—enabling a flow path acrossthe wound to the vacuum interface and then retrograde from the sealeddressing to the collection canister. An abrasive quality of the ventralsurface of some embodiments of the single layer dressing aids inmechanical debridement.

FIG. 1M depicts a cross-section of a single layer dressing. Thesingle-tube embodiment of FIG. 1M shows a cross sectional drawing of asingle tubing system 180 with a thin layer of netting, mesh 181 or thinperforated or nonperforated film connecting the irrigation and vacuumtubes. By “single-tube” (or “single lumen”) it is meant that the tubesare positioned singly throughout the layer, rather than in pairs (ormultiples). The connecting material 181 (e.g. mesh) aids in maintainingthe spatial relationship of the tubes, provides structural integrity tothe dressing and can allow for passage of fluid or gas around the tubes.The dual-tube embodiment 182 of FIG. 1M is a similar design, except witha dual lumen tube or two completely separate tubing systems. In the duallumen embodiment 182 the vacuum tubes and irrigation tubes are routedadjacent to each other, with the pairs of tubes connected by the webbingmaterial 181 (e.g. mesh). Typically, one of the dual tubes is dedicatedto vacuum, while the other is dedicated to irrigant. Yet otherembodiments involve additional tubes, for example, a triple-tubeembodiment. The third tube, which typically runs parallel to the othertwo, can be used for another purpose, e.g., dedicated to carrying amedical agent, or as a redundant spare tube in the event of afailure/clogging of the vacuum or irrigant tubing system.

FIG. 1N depicts the flow of fluid from one tubing system which is anirrigation system to another suction system. In view 190 a single lumensystem allows flow from one tube to another tube spatially connected bythe material between them. In this manner, the flow occurs across thewound which is positioned below the tubes. The additional dual lumenfigures depict a manner in which flow can be controlled in order todrive fluid across the wound surface. The path of least resistancepictured in the embodiment of view 190 would be out of one tube and backin the tube connected to it in the dual lumen system. By placing adividing ridge 188 that restricts flow between the two lumens aspictured in view 192 the fluid is forced to travel across the woundsurface to a neighboring tubing system.

FIG. 1O depicts the sealing layer 193 over top of the single layerdressing. This thin film would be airtight and have adhesive on some orall of its ventral surface to create a seal over the wound and allow fornegative pressure to be applied. In various embodiments, a thin (e.g. <1mm) film of plastic or polymer may be used for the sealing layer 193.Commercially available products which are similar to the designenvisioned are Tegaderm™ or Ioban™. The embodiment shown in view 194 and196 of FIG. 1O features an airtight sealing layer 193 over the singlelayer dressing's underlying tubular network. This same sealing layerconfiguration can be used in conjunction with a multi-layered unifieddressing as well. The sealing layer 193 is affixed to the centralportion of the single layer dressing at fabrication, to create a unifiedairtight dorsal surface—that is, the surface of the dressing facing awayfrom the wound, through which pass the connection tubing for vacuum andirrigation. To use the sealing layer 193, it may be unfolded from itsfolded state, the paper strips covering the adhesive removed (if any),and then the sealing layer 193, may be sealed in an airtight manner tothe dorsal surface of the dressing and patient's skin around the woundto produce a closed space under the dressing. This airtight seal isfurther achieved by placing adhesive sealing sheets on top of thesealing layer of the single layer dressing and the surrounding skinmargins to complete the seal, making this embodiment unidirectional andunified in its effect. Alternatively, the sealing layer 193 can have anapron-like extension that has adhesive on its ventral surface, coveredby peel-away paper backing. This can be used to make or initiate theseal of the dressing to the skin at the margins of the wound. Theconnection tubing entering the dressing, the airtight sealing layer andthe single layer dressing are composite, that is they are fabricated asa single unit. The sealing layer 193 is air-tight and water-tightserving as the dorsal most layer of the dressing. The dorsal surface ofthe sealing layer 193 can be “tacky” or possess a sticky quality thatserves to further improve the adhesion of the adhesive sealing sheets tothe sealing layer. This tacky portion can be covered with a removablefilm or paper backing, that preserves the purity of the tackiness whennot in use. Separate adhesive sealing sheets are then placed at theperiphery to seal the sealing layer 193 of the dressing to the woundmargins.

In some embodiments, the adhesive sealing sheet may be united with thesealing layer 193 of the single layer dressing, into a unified compositesealing layer, possessing an apron-like extension with adhesive on theventral surface of the apron. In other embodiments the sealing layer 193may be affixed only to the tubing connection point at the dorsal centralsurface of the single layer dressing. The remaining portions, includingan apron-like extension may have adhesive on the ventral surface of thesealing layer. Typically this adhesive portion is covered with peel-awaypaper backing. The adhesive on the sealing layer 193 may have adhesiveover its entire extent, or only at the peripheral portion, e.g., fromthe peripheral edge inwards by a distance of from to 2 to 10 cm. Thiscreates a semi-adhesive strip at the peripheral edge as narrow as 2 cmwide in some embodiments, and up to 10 cm wide in other embodiments. Thesealing layer 193 may be configured so it can be folded back on itselfin the midline, for example, as shown in embodiment 196 of FIG. 1O. Thesingle layer tubular portion is cut to the size of the wound and thenplaced into the wound. The incorporated sealing layer 193 withadhesive—a part of the unified dressing structure—is then unfolded tocover the single layer dressing and removably affix it to the skin atthe margins of the wound, affecting a sealed closed system between thedressing and the patient. The peel-away backing of this adhesive open atthe midline, so the periphery can bet cut to match the dimensions of thewound as well, while still preserving the peel-away backing feature. Inthis context, the term “removably affixed” means that it can be fastened(e.g., stuck on with an adhesive) in a manner that allows later removal,that is, it is not permanently affixed to the patient, or affixed sostrongly that it will tear or otherwise damage healthy skin uponremoval.

In other embodiments, the dorsal side (surface facing away from thewound) of a dorsal most apron-like sealing layer that is centrallyaffixed to the tubing interface of the dressing, has at the periphery atacky substance (similar in adhesive quality to 3-M Post-It® notepaper), which is covered with peel-away paper backing. This is removedwhen the dressing is set to be removably affixed to the patient, andthis tacky substance serves as an adhesion enhancer for the adhesivesealing sheets used to seal the apron (and underlying dressing) to thepatient. These adhesive sealing sheets are placed over this tackysubstance and onto the skin at the margins of the wound to affect thisseal. This allows for 1 to 2 inch strips only to be applied to thedressing at its periphery instead of covering the entire dressing with athin adhesive film, since the dressing itself is airtight byfabrication, as opposed to the piecemeal conventional dressings, whichrequire the air tight seal to be created in situ at the level of thewound over the entire dressing surface and adjacent skin margins.

FIG. 1P depicts an embodiment with a top sealing layer 185 sealed to thedressing 187 in a central location 189. This top sealing layer can beattached through fabrication to either a single layer or multi-layerunified dressing 187. The sealing layer 185 can be folded up into afolded state for packaging in a packaging wrapper or other removablecovering. It consists of a thin (e.g. <1 mm) pliable plastic or polymerwith an adhesive substance on the ventral side. Commercially availableproducts which are similar to the design envisioned are Tegaderm™ orIoban™. An adhesive cover can also be used to allow for placing thesealing layer 185 when ready. The sealing layer 185 can then be unfoldedto an unfolded state and trimmed separately from the dressing 187, so asto fit over the dressing 187 which has itself been trimmed to fit thewound. Once each item is trimmed to size—that is, the dressing 187 tothe size of the wound and the sealing layer 185 to a size larger thanthe wound—the sealing layer 185 is placed over the dressing 187 as itlies in the wound bed and affixed to the skin at the wounds margins tocreate an airtight system.

FIG. 1Q depicts an embodiment with an airtight film 175 over top ofwhole dressing 177, which again could be the single layer or multi-layerembodiment of the MWT layered dressing design. The material may be athin (e.g. <1 mm) film of plastic or polymer. Commercially availableproducts which are similar to the design envisioned are Tegaderm™ orIoban™. The airtight film 175, is typically affixed permanently atfabrication to the dorsal surface of the entire dressing 177 and inapron containing embodiments this airtight film may extend peripheral tothe single layer tubing portion of the dressing, but there may beembodiments, in which the fixation of the sealing layer is partial, forinstance only being at the central tubing connection point. In someembodiments, the dorsal surface of the dressing 177 can have a stickydorsal surface to promote the seal between the airtight film175—sometimes called sealing layer 175—and the dressing. The inherentsealing layer 175 eliminates a common source of leakage and dressingfailure for conventional systems.

FIG. 1R depicts an embodiment with a central suction cavity. In thisimplementation the chamber is in a disk or cylinder shape. The disk hasa side wall 130 with pores 131 through it as well as a floor 132 withpores 131 to allow the passage of fluid or gas through it into thecentral collecting chamber. The figure depicts one way of reinforcingthe chamber to prevent collapse. In this depiction, the inside has aseries of ridges 134, walls or other structural components to preventcollapse that provides channels to a central suction tube insertionpoint.

FIG. 1S depicts an embodiment of a multi-flange design for the suctiondelivery to the dressing. In this embodiment there are several flanges141 that provide equal suction. This redundancy allows for the casewhere one flange becomes clogged. If a single flange is clogged thereare several others to continue providing suction.

FIGS. 2A-C depict embodiments of the single layer dressing with only atubing network without netting, mesh or thin perforated or nonperforatedfilm. The tubing is typically constructed from plastic or polymermaterial that is biologically inert. This embodiment of the vacuumtubing network may be placed into a wound and then covered by thecentrally affixed airtight sealing layer (also known as the covercomponent or covering layer). In other embodiments two tubing networks,one for vacuum and another for irrigation, rest ventral to the airtightsealing layer. In various embodiments the single layer dressing caneither collapse upon themselves in a controlled or random fashion as thewound volume is reduced, or the single layer dressing can be trimmed atits edges to conform to the shrinking size of the wound. This supportsthe wound approximation goal of MWT, by preventing resistance to woundapproximation that can occur related to the mass-effect of bulkynonideal wound fillers used in conventional dressings.

FIGS. 2A-C depict typical geometric arrangements for the irrigationtubing system and/or vacuum tubing system. This tubing system may beused with in various implementations across the MWT platform. It canstand-alone, as it does in the single layer dressing. It can also be afunctional element of either a layered dressing, as demonstrated in FIG.1B, or a unidirectional wound filler dressing, as demonstrated in FIG.12C. The perforations in this irrigation tubing system can be locatedthroughout along the length of the radial arms 205 and horizontaltraversing connectors 203—typically oriented only towards the ventral orlateral surface (not dorsal) or only at the terminal ends of the radialarms 205 of the tubing system. In the single layer dressing the spacebetween tubes 205 may be filled with netting, mesh or thin perforated ornonperforated film, while in the layered dressing, this space is vacantor filled with spacers and the tubes are held in their spatialrelationship, by being permanently affixed to the layering materialventral and dorsal to the tubing. In the unidirectional filler dressing,the space between the tubes may be filled with wound filler, as thetubing system is recessed into the ventral surface of the dressing. Invarious embodiments, the unidirectional dressing may have therapeuticadjuvants embedded or otherwise contained in or with the wound filler.

FIG. 2A illustrates a generic tubing layer suitable for use in a numberof the embodiments disclosed herein. The radial arms 201 are eachpositioned to extend radially in a peripheral direction from a centralconnection point of the tubing network and the horizontal transversingconnectors 203 connect between radial arms to produce a web pattern. Insome embodiments the horizontal transversing connectors 203 are simplybraces that hold the radial arms 201 in place. In other embodiments thehorizontal transversing connectors 203 are themselves tubes that providevacuum/irrigant flowpaths between the radial arms. This helps to promotean even dispersal of vacuum and/or irrigant, and also provides alternatefluid flow paths in the event a fluid passage hole on a tube becomesblocked. In other embodiments, e.g., as depicted in FIG. 2B, the tubingsystem only has radial arms 205, with no transverse connectors. Thisgeometric configuration of the tubing system can be configured tosupport a collapsing effect, in response to progressive woundapproximation, directed by modules of the MWT system, e.g a woundapproximating module.

One or more fluid passage hole perforations are provided on each of thetubes to facilitate flow of the vacuum and irrigant. The fluid passageholes may be configured on any side of the tubes, depending upon thenature of the wounds intended to be treated. Typically, there areperforations on three sides of the tube—downward (ventral), left andright—with the top (dorsal) side remaining without perforations. In someembodiments the perforations are only provided on the sides, left andright, while other embodiments the perforations are provided on thebottom (ventral) but not the sides of the tubes. In some embodiments theperforations have a uniform size. In other embodiments the perforationsare smaller towards the center of the tube web where the pressure (orvacuum) is greatest, with larger perforations provided towards the outerpart of the web where the pressure (or vacuum) is less strong. This isdone in a manner to promote an even flow of vacuum and fluids from thecentermost holes to the holes toward the periphery of the wound. Thelocation and geometry of the holes aids in directing irrigant fluid ontothe wound surface. This can be an advantage over conventional systemswith holes facing away from the wound or randomly distributed bynon-tubular type wound filling materials (e.g., sponge or gauze baseddressings) which may allow flow of the irrigant away from the wound,preventing the irrigant from coming in contact with the wound to assistin wound cleansing.

FIG. 2B depicts an embodiment in which the individual perforated tubes205 extend outward as spokes from the central connection point in aradial pattern. The tubes 205 are configured in a radial patternextending outward in a lateral direction from the center which serves asthe delivery point for vacuum and/or irrigant. The “lateral” direction,in the present context, is the direction side-to-side, generally overthe surface of the wound, (e.g., approximately 90 degrees from thedorsal to ventral line is laterally). It should be noted that thevarious components (e.g., tubes 205) tend to be flexible. Although theyare said to extend laterally they may flex to conform to the contours ofthe patient's body and actually be at somewhat different angles than 90degrees. For example, the tubes 205 extending laterally may in fact beat 90+/−15 degrees from the dorsal to ventral line outward from thewound. In the embodiment of FIG. 2B the radial arms 205 may be trimmedto shorter lengths in order to shape the radial pattern tube network inorder to alter the coverage size of the tube network to accommodate theshape of a wound. These radial spokes can also zig zag or curve withinthe plane of the dressing to allow for more coverage of the wound withthe irrigant. The dressing itself including the radial tubing may betrimmed in order to fit specific wounds during application. Since theradial tubing design allows the dressing and tubing can be cut to sizeat any location and the system will still function as designed.

FIG. 2C demonstrates a radial arm embodiment, that has an additionalperipheral ring 207 of tubing or spacing material. The peripheral ring207, when configured as operable tubing, is in fluidic connection withthe radial arms 205 and central connection point. That is, fluid (orvacuum) that flows through the radial arms 205 also flows through theperipheral ring 207. In one embodiment of the tubular system, there areno perforations in the radial arms 205, only in the peripheral ring 207,and any perforations created by cutting the peripheral ring 207 orradial arms 205 to fit the size of the wound. This embodiment promotesvacuum and/or irrigant to reach the periphery of the wound. In allembodiments of the tubing system, the tubes 205 and 207 can remain freeof material interspaced between the tubes or netting, mesh, thinperforated film or other wound filling materials (e.g. sponge) can beplaced between the tubes to connect the tubing and/or preserve thespacing between the tubing. The tubing may be plastic or polymer with aninner diameter in the range of 1-3 mm. The outer diameter may be in therange of 3-5 mm. The size of the whole construct could vary based onfunction and use. Again sizes could be marked as large (for instance 6inches in diameter), medium (for instance 3 inches in diameter) andsmall (for instance 1-2 inches in diameter). Lastly, since many woundsthat would be ideally treated by the MWT platform of dressings have amore elliptical shape, the tubing systems and layered dressingspossessing these tubing systems, may be configured in an ellipticalshape with a long and short axis. Whether circular, elliptical or othergeometry, the basic design features that have been described hereinwhich promote universal customization and applicability would remainpresent in all geometries.

The vacuum tubing system, for example, the tubing layer depicted inFIGS. 2A-C, is typically in fluidic communication with the collectioncanister (e.g., canister 106 of FIG. 1A). In this way, the vacuum tubingsystem is configured so that fluids, either liquid or gas, can flow tothe collection canister 106. Typically, this is achieved via a vacuumconnection tubing (e.g., vacuum connection tubing 109 of FIG. 1C) thatconnects the collection canister to the tubing connection point on thedorsal surface of the dressing. The connection point for the vacuumtubing may be a specialized component called the vacuum interfacechamber (e.g., vacuum interface chamber 121 of FIG. 1C) or the vacuuminterface flange (in embodiments where there is no ventral floor). Thisserves to better distribute the vacuum to all portions of the sealedwound and to prevent system failure from blockages at a single point.When vacuum is applied the tubing system of FIGS. 2A-C transmits fluidsretrograde toward the collection canister 106. In the typicalembodiment, the tubing connection point has a one-way valve that avoidsback-flow of wound effluent, preventing effluent from flowing back intothe vacuum interface chamber or flange and possibly to the wound. With aone-way valve in place the wound effluent can only progress retrogradefrom the wound. Once the wound effluent crosses the one-way valve in thetubing connection point and enters the vacuum connection tubing, itcannot return to the wound or interface chamber.

When irrigants are pumped through the independent irrigation tubingsystem the flow of irrigant fluids occurs in the opposite direction(e.g. towards the wound in an antegrade fashion). Instead of activelypumping fluid (e.g. with the use of a motorized pump) through thetubing, the fluid can be delivered passively under the influence ofgravity or vacuum can be the driving force to draw fluid across thewound surface and cleanse the wound. This vacuum, under the regulationof the EVR, can be programmed to provide intermittent bursts of negativepressure to allow maximal irrigation and agitation of the irrigant, topromote mixing at the wound surface and assist in the micro-debridementaspects of the MWT system.

In some embodiments, there is one tubular network of lines that servesthe dual purpose of providing both vacuum and irritation, at differenttimes. This embodiment must be switched between vacuum and irrigationsince there is only one tube system. In layered dressing embodiments thevacuum lines and irrigation lines may be provided in different layers.That is, the irrigant lines may be configured in one layer, with thevacuum lines being configured in another layer. In yet other embodimentsthe irrigant lines and vacuum lines may be provided within the samelayer, but using independent tube networks that are controlledseparately. Netting, mesh or thin film can be affixed between the tubingor not. When vacuum and irrigation delivery is separated into twodistinct tubular systems, the irrigation layer is placed closest to thewound, so that the flow path is from irrigation influx, to/across thewound surface and then dorsally (away from the wound) to the vacuumsystem.

FIG. 3A is a block diagram describing an embodiment of the reverse pulselavage system. Reverse pulse lavage is a novel concept for applyingirrigation to a wound surface under a NPWT or MWT dressing. It consistsof intermittent, controlled and programmable bursts of negative pressurevia the vacuum tubing system/interface chamber/flange, which along withor without gravity, acts to draw the irrigant from its source, throughits dedicated tubing system, across a one-way valve and then across thewound to be suctioned and delivered to the collection canister, e.g., asdescribed in FIG. 3A. This system, removes the need for a positivepressure pump or gravity fed in-flow as the propulsion force fordelivering irrigant to the wound surface. The pulsed nature of reversepulse lavage, acts to agitate the fluid as it crosses the wound surface,to facilitate mixing of irrigant with wound surface biologicalcollections (e.g., bio-films). Further this method of lavage, unlikepositive-pressure pulse lavage (especially in the setting ofhigh-pressure lavage often used in surgical irrigation), avoids thepotential negative effects of driving wound surface biological debris orforeign material debris deeper into the wound and/or disturbing thenormal wound healing process. The fluidic agitation produced by reversepulse lavage provides a secondary mechanical effect which will improvethe cleansing of the wound surface, bacterial burden reduction andmaintenance of a healthy, moist wound bed surface. Lastly, this methodtends to reduce the chance of irrigant pooling, which can erode theintegrity of the dressing seal. Prevention of pooling can be assisted bya one way valve in the tubing connection point for the vacuum connectiontubing at the dorsal surface of the vacuum interface chamber or flange.By preventing back flow from the vacuum connection tubing, the irrigantis forced to move away from the dressing and not back into it to allowpooling and recontamination at the wound surface.

The integrated wound dressing system of various embodiments isconfigured to fluidically connect a dressing component, connectiontubing and collection canister all under the control of a control unitsuch as an electronic vacuum regulator (EVR). Conventional systemstypically use the vacuum tubing network for the added purpose ofirrigation when delivering a fluid irrigant to the wound. The variousembodiments disclosed herein provide an improved system for deliveringirrigants and/or adjunct therapies. In various embodiments describedherein the vacuum tube system is separate from the irrigation system,from source to the sealed dressing and/or wound surface, to produce theintended wound surface irrigation effect. In such embodiments the vacuumtubes (or vacuum interface chamber) are fluidically separate from theirrigation system. In this way, the mixing point for irrigant deliveredto the wound via the irrigation system and the negative pressuresuctioning the irrigant and wound fluid from the wound is the woundsurface itself. Separation of vacuum and irrigation flow paths allowsfor simultaneous irrigation and suction, similar to a pulse lavagedevice. This simultaneous application of irrigation and suction helps toprevent the pooling of irrigant fluid and reinforces the intended flowpath of irrigation across the wound surface. This is an improvement overa common flaw of conventional systems that have dressings which have allor a portion of the irrigation flow-path shared with the vacuumflow-path. Lavage irrigation is not possible in conventional devices inwhich the in-flow and out-flow systems are not separated at the woundsurface. This design flaw in conventional NPWT devices which possessirrigation systems potentially returns devitalized tissue and microbialburden back to the wound surface by forcing in-flowing irrigation fluidthrough shared out-flow tubing or by pushing irrigation fluid acrossexudate saturated wound filler, thereby re-contaminating the woundsurface.

Moreover, the present inventors recognized another common flaw in themanner the conventional devices handled irrigation in the setting ofNPWT dressings. Since conventional devices call for some or all of thetubing or other forms of flow-paths in the system to be shared betweenthese two mutually exclusive functions, these functions must be runsequentially rather than simultaneously. This leads to a problematicsituation in conventional NPWT dressings with irrigation wherein thewound filler becomes saturated and/or fluid pools. When this happens toconventional dressings the seal maybe lost and the dressing iscompromised. To avoid saturating the dressing, conventional systemslimit the time the irrigant is applied. However, in doing this theconventional systems reduce the amount of irrigant actually reaching thewound, if the irrigant fully traverses the wound filler and reaches thewound at all. In conventional systems, even if the irrigant reaches thewound, it generally reaches through diffusion or instillation throughthe wound filler since it is delivered to the dorsal side of the woundfiller, away from the wound. This wound filler is saturated withexudate, devitalized tissue and microbes, which are then driven/floatedtowards the wound. The propagation of “dirty” material within the woundfiller towards the wound surface is contra-productive to the intendedwound cleansing effect.

Returning to FIG. 3A, this figure provides a block diagram forembodiments of a reverse pulse lavage system. The method begins at 301and proceeds to 303 where the system is connected to an irrigationsource such as an IV bag. In block 305 the bag is attached to a tubingsystem to deliver the irrigant to the dressing, and on to the wound. Inaccordance with block 307 there is a one way valve that allows fluid outof the irrigant source only when negative pressure is applied to thesystem. In other words, irrigation is released only when sucked out ofthe source by the EVR regulated suction. Once the irrigant passesthrough the valve, it continues down the tubing where it passes througha crimp valve, as per block 309. The crimp valve can be engaged toprevent irrigation regardless of suction or negative pressure if noirrigation is desired. This is a shut off valve for reverse pulse lavageand other forms of irrigation within the MWT platform. Once the irrigantfluid is passed through the crimp valve, it passes into the dressingaccording to block 311 through its series of tubing and the irrigant isdeposited on the wound surface. In block 313 the irrigant is forcedacross the wound surface to help debride the wound. The suction will beperformed in an alternating manner to allow short bursts of suction, asper block 315, in order to increase the amount of irritation across thewound surface and increase agitation of the irrigant as it crosses thewound surface.

Once the irrigant crosses the wound surface it is suctioned back intothe dressing tubing system at the central vacuum interface chamberaccording to block 317. The irrigant now travels through the suctiontubing system away from the wound surface. As it exits the dressing, aone way valve is present on the tubing, in accordance with block 319.This valve prevents backflow of the irrigant as it leaves the dressing.In block 321 the irrigant then travels through the suction tubingtowards the collection canister. The collection canister of block 323 isconnected to an EVR of block 325 via an additional tubing that may ormay not have a biological filter, block 327, to clean the air as itenters the EVR. In accordance with block 329 the EVR is programmable tocontrol the timing, duration, strength as well as other factors of thesuction which drives the system. The method proceeds from block 329 backto block 307 where the EVR opens the one way valve with applied suctionto start the suction segment of the cycle.

FIG. 3B is a block diagram pertaining to the reverse pulse lavage systemsimilar to FIG. 3A, but depicting embodiments in which the irrigationsource can be alternated between a fluid irrigation and gaseousirrigant. One benefit of this system is that it can be controlled by avalve that may be configured to alternate between the multipleirrigants. Using a gaseous irrigant between bursts of fluid helps toprevent pooling. The gaseous irrigant can clear the system of fluidsbefore another burst of fluid is passed through the system. Further, gasirrigant will aerate the liquid phase irrigant, which can assist in theirrigation function and deliver these gases directly to the woundsurface to promote healing.

FIG. 4 depicts an embodiment of a multi-looped accessory dressingconfigured to be attached to the underside of the standard dressing. Themultiple loops 401 in this embodiment can be arranged to fill a cavitarywound. FIG. 400 depicts the multi-looped dressing with four differentloops that may be configured to provide different functions. Forexample, some loops may provide irrigation while others provide suction.In one embodiment the function is alternated, so one loop providesirrigation and the adjacent loop provides suction. By separating thefunction, the irrigant must travel out of the tubing system into thewound before entering the suction loops. FIG. 420 depicts an embodimentin which a loop possesses the ability to both irrigate and to providesuction. This embodiment is designed with a blockage 403 within thetubing. The tube 401 has an irrigation portion 407 and a vacuum portion405. The blockage 403 forces the irrigant to leave the tubing from theirrigation portion 407, travel across the wound, and then enter thevacuum portion 405 of the tubing.

FIG. 5A depicts an embodiment of wound dressings 501, 503 and 505configured to be attached in series to allow the same suction andirrigation source to provide multiple therapeutic dressing with theneeded irrigation and suction. This capability is enabled by a set ofports 507, 509 and 511 at the junction of the dressing and the tubing.There is a quick connect at the port that allows irrigant to continuefrom the tubing to the next dressing tubing without all of the irrigantgoing into the initial dressing. In the embodiment depicted in FIG. 5A,if dressing 505 is the last dressing in the series the port 511 can beclosed (e.g. capped) to avoid leakages in the irrigant and vacuum lines.In another embodiment the port 511 can also be connected to the sourceof vacuum and irrigant, so suction and fluids are provided to the seriesof dressings at both ends. Valves just distal to the port allow thepressures to be adjust for the irrigant and vacuum, and aid inpreventing mixing of irrigants and cross contamination betweendressings. This embodiment allows a single EVR to monitor and functionas a negative pressure source and irrigator for multiple dressings. TheEVR may be configured to provide separate monitoring displays andcontrols for each of the multiple dressings.

FIG. 5B depicts two embodiments 520 and 540 in which a wall suction orother suction source can be used to provide suction for multipledressings. This suction source can be any suction device found intypical hospital or military settings. The first diagram shows asplitter that can separate the vacuum source into multiple suctionoutlets. In this case, multiple EVRs can be used to control the multiplesuction sources created by the splitter. In other embodiments amulti-channel EVR is used to control the multiple negative pressuresources. The first diagram depicts a plastic or metal or polymermaterial with dimensions approximately 3 inches deep by 3 inches tall byapproximately 3-12 inches wide depending on the number of splitsrequired or desired. The second diagram depicts a single suction sourcewith a single EVR. However, the EVR is capable of splitting the suctionand providing separate EVR monitoring for multiple dressings through thesame device. Again the size of this could vary based on design andfunction of other components as well as the number of out ports. Thesize may be determined by number of splits as well as additionalfunctions built into the EVR.

FIG. 6A depicts a number of views 610 to 660 of an embodiment of aseparating system for gas and fluid mixtures. This system allows forseparation without the use of gravity and a stationary canister. It usesa malleable bag 601 that is filled with hyper-absorbent spheres 603. Thespheres 603 maintain their size to allow the mixture to pass through andbetween them (refer, for example, to view 620). They can be made ofsuper absorbent materials such as but not limited to sodiumpolyacrylate. These spheres may be uniform is size or vary in sizesbetween 2 mm in diameter to ≧1 cm in diameter. These spheres could besmaller or bigger as needed. As the mixture passes through the spheres603, the air is dried. In some embodiments (refer, for example, to view630) the hyper-absorbent material of spheres 603 are placed in a cagetype structure 605 to prevent the closure of air passage ways.Additionally, multiple bags can be attached in series to allow for extradrying. The expectation is that the air may be dried sufficiently suchthat at the end of the collection bag there would be no fluid to bedeposited on clothing or other surroundings coming in contact with theair. As additional mixture or fluid is added the spheres 603 proximateto the entrance will become saturated as shown in 640. As more fluid isadded, more of the spheres 603 throughout the malleable bag 601 to theexit will fill with fluid, as shown in 650. Ultimately, all of thespheres 603 in the entire container 601 will become filled, as shown in660. At that point an indicator signals the saturation of the container,to allow replacement of the bag 601. The alarm can be accomplishedthrough a digital humidity monitor and alarm similar to but not limitedto WHDZ (Manufacturer) AMT-123 or NSmartIOEM (manufacturer)STH702/STH703. The connection to the tubing is a quick connect to alloweasy connection and disconnection. Quick connects can be obtained suchas ones provide by but not limited to Colder Products Company (St Paul,Minn.).

FIG. 6B depicts an embodiment of an alternate means to separate gas andfluid mixtures. Instead of spheres for separation, the presentembodiment uses a cylinder type design, for example, featuring multiplecylinders 671 containing hyper-absorbent material. Crosssection view 680depicts the hyper-absorbent material 673 within the cylinder 671. Thecylinders 671 are positioned pass the mixture through thehyper-absorbent material as it is flowing toward the canister. Byexposing the mixture to the multiple rings of hyper-absorbent material673, the air is dried and passes out the opposite end without fluid. Asin the embodiment of View 670, an indicator is configured to signal whenthe hyper-absorbent material 673 is fully saturated and it is time tochange the canister 671.

FIG. 7A depicts an embodiment of a bladder 701 (sometimes called apositive pressure device) configured for placement over a standarddressing 703. View 710 shows the bladder 701 being placed over the woundon a patient's leg. Without an external sleeve to direct the pressureand force towards the leg, the bladder expands away from the extremity,as shown in views 720 and 730. When external sleeve 705 is wrappedaround the extremity, as shown in views 740 and 750, the bladder 701expands along the wound compressing the dressing 703 down on the woundsimilar to a sequential compression device (SDC). This arrangementallows for the edema to be compressed out of the injured tissue whilealso pressing the dressing down on the wound.

This bladder can be made of a less elastic material on the dorsal orouter side such as plastic, polymer, latex, vinyl or rubber. The moreelastic ventral side generally allows for more expansion and be a latex,rubber, plastic or polymer material. The size may be varied based on thesize of the wound. It could be designed in different sizes to matchdifferent size dressings from 2-3 inches in diameter to ≧12 inches indiameter.

The bladder design in this embodiment differs from prior art in severalaspects (Shuler Published U.S. Patent Application Number:US2011/0054283A1). Its design is unidirectional in order to allow thebladder to expand to the wound and is modular so it is not built intothe dressing which allows for completely independent use. This designallows the bladder to be placed directly over the wound in order tocompress the dressing onto the wound and reinforce the seal of thedressing. It also promotes micromotion of the dressing at the woundsurface to aid in micro-debridement of the wound. Additionally, thebladder in combination with the wound approximating device assists inclosing the wound by cyclic loading of the skin edges with interveningapproximation under the continuous pulling force of the woundapproximating device. The inflatable bladder may be controlled tostretch tissues before applying an approximation device. The pressure inthe bladder typically allows for 2-10 newtons, or more, to be placed onthe skin edges. The pressure could be monitored from the EVR to controlthe amount of pressure exerted on the wound or skin edges based on theamount of gas or fluid inserted into the bladder. The gas could be, butnot limited to room air, oxygen, inert gas such as Nitrogen.Alternatively, a fluid such as tap water, saline or sterile water can beused to inflate the bladder. The fluids temperature can be varied todeliver either a cooling or warming effect depending on the clinicalsetting and desires of the treating clinician.

FIG. 7B depicts an embodiment of a unidirectional bladder. In thisfigure the bladder 711 is displayed deflated in view 760, and displayedinflated 770. A rigid top portion 707 of the bladder 711 is designed tobe less flexible (more rigid) than the bottom flexible portion 709 ofthe bladder 711. The ventral side—the flexible portion 709—is a muchmore pliable material that expands down and outwardly. View 780 and 790show a crosssection of the unidirectional bladder 711 positioned on anextremity (e.g., a leg), covered with a sleeve. View 790 illustrates thebladder in an inflated state with the flexible portion 709 of bladder711 filling the wound bed and applying an even pressure throughout thewound. The inflatable bladder can be maintained in an inflated state forany amount of time to apply pressure to tissue beneath the inflatablebladder. A more rigid bladder would be likely to cause pressure to beapplied to certain areas with little or no pressure being applied toother areas, thus creating pressure points and not filling the woundevenly. View 795 demonstrates how the pliable bladder embodiment 711fills an uneven wound surface, providing even pressure on the wounddressing, and providing even pressure on the sealing layer above thedressing to reinforce the seal. This can only occur with a sleeve 705,backboard structure or simply using a more rigid material to form thedorsal surface of the bladder with means to prevent the bladder fromlifting away from the wound and dressing, with the ultimate goal ofdirecting the force of the bladder towards the wound surface.

This bladder can be inflated by manual control using a manual small pumpsimilar to aircasts and boots used for lower extremity injuries(Aircasts walking boot). Alternatively, the inflation and deflation canbe activated by the EVR or otherwise controlled by a pressure controlunit.

FIG. 8A depicts an embodiment of a wound approximating device 801(sometimes called a tensioning device) acting as a backboard, to directthe positive pressure bladder 803 towards the wound. The approximatingdevice 801, when used in this manner, replaces the sleeve 705 of FIG.7A. View 810 depicts two specific forces being demonstrated. Thedownward force of the positive pressure bladder 803 can have multiplebeneficial effects. The positive pressure bladder 803 compresses thedressing to the leg helping to insure the dressing contacts the woundand covers the uneven surface of the wound. The positive pressurebladder 803 reinforces the seal by putting pressure on the sealinglayer. The positive pressure bladder 803 creates micro-motion betweenthe dressing and the wound. This micro-motion allows the wound to bedebrided without straining the seal. In various embodiments the motionmay be on the order of <1-5 mm of motion. The positive pressure bladder803 helps in pumping edema out of the tissue similar to an sequentialcompression device (SCD). The positive pressure bladder 803 preventsvenous congestion and promotes blood flow in the wound similar to anSCD. The positive pressure bladder 803 pumps fluid or irrigant out ofthe dressing and back into the suction tubing to promote wounddebridement. View 810 depicts the downward force onto the wound that isapplied by the approximating device as it is pushed away from the wound.When this occurs the force is transmitted to the skin edges and pullsthe skin edges in closer proximity.

A unique design feature of the approximating device is the modularaspects of the design. This aspect of the device is completely separateof any dressing component. Prior devices with similar attributes, havethe wound approximating elements fabricated into the dressing itself.The design described herein separates the dressing from the approximatorand allows for both to be used completely independent of each other.Prior art has a tensioner embedded into the sponge dressing. (ShulerPublished U.S. Patent Application Number: US2011/0054283A1) Due to itsmodule design, the approximating device can also be completely removedfrom the dressing after application to allow the seal or wound to beinspected without adversely affecting the dressing.

The outer shell and central shaft of the approximating device may bebuilt from a plastic or polymer material. The longitudinal outer shellcan be made to have some flexibility to allow the device to conform todifferent parts of the body and different shapes. The ribbons may bemade of either a plastic, nylon, rubber or other polymer.

Views 800 and 810 shows how the approximating device 801 is placed ontop of the bladder 803, which itself is on top of the sealing layer andthe dressing. The peripheral edges of approximating device 801 areattached to the patient's skin around the edges of the wound, e.g., withstaples 805. As the bladder 803 is inflated it tends to push away fromthe wound surface. The approximating device 801 with its spring loadedribbons is able to exert an inward (e.g. approximating) force toward thecenter of the wound. The peripheral removable fixation of the woundapproximating device to the patient, prevents the bladder 803 fromexpanding away from the wound while also increasing the approximatingforce on the skin edges preventing retraction and promotingapproximation of the skin.

FIG. 8B depicts an embodiment of the approximating device, illustratingits ability to be attached to the skin edges (refer, for example, toview 620). A single or multiple pull tabs 821 can be used to connect themultiple ribbons 823 (refer, for example, to view 630) that exert aforce on the skin edges. In some embodiments the tab 821 is made of asoft enough material that one or more surgical staples 825 or sutures(or other fixation device) can be used to secure the tab to the skin, asshown in view 840. The tab 821 is typically positioned at the skin woundedge or further away from the edge where more healthy skin may exist.The attachment of tab 821 to the skin can be assisted through the use ofadhesive on the ventral part of tab 821. Such use of adhesive canreinforce the sealing layer over the wound. A covering (e.g., peel-offpapers) over the adhesive can be peeled off to allow for easy placementof the tab on the skin. The tab 821 can then be stapled into placemaking application quick and easy.

FIG. 9A depicts multiple ways to detach the approximating ribbons 923from the device itself. The attachment of the approximating ribbons 923may be accomplished in a number of different ways. For example, threesuch means of are by use of a snap 931, hook-and-loop fasteners 933(e.g., Velcro™), a hook and hole fastener 935 or a press-fit clamp thatallows for the attachment point of the ribbons to be changed to anypoint along the ribbon. In this last embodiment of a fastening(removably affixing) technique for the ribbons, any slack in theribbons, specifically at the ends of the wound's long axis, can bepulled through the press-fit clamp and cut to length. Views 910 and 920demonstrates three of these mechanisms used to accomplish this task. Thepurpose of being able to release the ribbons is twofold. The firstpurpose is to remove the approximating device completely. This might beneeded to inspect the dressing as in a leak, the wound may be closed orthere may be some concern for increased pressures within the tissuebelow. The second purpose may be that one area of the wound is closedand another is not. When the ribbons are all attached to the samecentral crankshaft, once one area is closed, that area could preventother areas from being approximated. By being able to release specificribbons, the closed areas can be released to allow other open areas ofthe wound to be approximated.

FIG. 9B depicts the support ribbons exerting forces on specific areas ofthe wound. In the example illustrated in view 930, the middle aspect ofthe wound is wider than the edges of the wound, which is a very commonwound scenario. View 940 shows all ribbons 923 attached to the wound. Asthe wound closes down over time, the corners on the top and bottomapproximate or efface. If left alone—that is, if the ribbons 923 werenot detached or altered—the middle of the wound may not continue to beapproximated since the ribbons 923 in the corners would preventadditional approximating forces being exerted through the centralcrankshaft 970 onto the ribbons removably attached to the middle of thewound. Alternatively, the corners could be pulled onto each other,over-lapping and producing a state of over-approximation. Neither ofthese are optimal outcomes. By releasing the top and bottom ribbons 923as shown in view 950, the middle ribbon 923 (still attached) is now ableto continue to approximate the wound edges in the middle of the wound.These ribbons are typically configured to be 0.5 to 3 cm in width, andsufficiently thin to avoid rolling up upon themselves (e.g., 0.5 to 2mm). The ribbons may be made out of plastic, rubber, latex, polymer,nylon, vinyl, silk, or other like type of flexible elastic or nonelasticmaterial. In another embodiment the central connection point (e.g.origin) of the ribbons to the central crankshaft 970 of the woundapproximating device, can be differential, exerting more approximatingforce and/or resulting in greater excursion of some ribbonspreferentially over others, to aim for a consistant rate of wound edgeapproximation and/or to avoid a pulling force on a single or few ribbonsthat is above a safe threshold (e.g. 10N) for pulling on the skinmargin. One means for constructing this differential approximatingcrankshaft 970 is by varying the diameters of the central crankshaft970, such that the central most portion has a greater diameter and theterminal poles (e.g. the 2 ends of the shaft) have a lesser diameter,such that with each rotation of the shaft, the excursion of the centralmost ribbons around the shaft, and thereby the approximation of theaffixed skin margins, is greater than the approximation occurring at theterminal poles. The variation in diameters of the differentialcrankshaft 970 is typically through construction, but could becustomizable through the injection of a fluid or semi-fluid into thecentral crankshaft 970 at locations, in which a greater approximatingforce or ribbon excursion is necessary.

FIG. 10 depicts a cutaway view of wound interface chamber depictingmultiple vacuum flow paths 1007 created by the internal risers andperforations in the peripheral (or lateral) wall and vental wall of thechamber. Some embodiments disclosed herein feature a central wound orvacuum interface chamber that serves as a communication point betweenthe vacuum source and effluent exiting the dressing. The chamber can bea relatively thin walled, flexible closed cell, with internal risers tokeep the walls of the chamber from collapsing on each other whennegative pressure is applied. The material the chamber is constructedout of may be plastic, rubber, metal or polymer. The diameter of thechamber may be for <1 to 3 cm in diameter and <1 to 1 cm in height. Thesize may vary based on the size of the dressing. The risers may be from<1-3 mm in thickness to resist chamber compression. The ventral (facingthe wound) side and peripheral (lateral) wall have multiple perforationsto communicate the vacuum entering the dressing across the dimensions ofthe wound sealed under the dressing. This embodiment resembles a showerhead, but in reverse, that is, a showerhead that projects water antegrade. This embodiment describes the retrograde flow-path for the vacuumand evacuated effluent. There is a central vacuum source connectiontubing that communicates with a central cavity in the vacuum interfacechamber in an airtight fashion, with a multitude of vacuum flow-pathscreated by the internal risers and perforations, which “showers” vacuumonto the sealed wound. Alternatively, the chamber can be composed of asolid piece of medical grade polymer with a multitude of internalpathways that come to a central point that is in communication with thevacuum source. The internal pathways are separated from each other bythe medical grade polymer, which serves to add structure to the chamberand maintain a specified spatial orientation of the pathways. Lastly,the walls of the vacuum interface chamber can be thick enough andconstructed of material that prevents collapse of the internal space ofthe vacuum interface chamber. Either of these two embodiment additionalelements can pass through the central vacuum interface (flange orchamber) as depicted in FIG. 1C.

FIGS. 11A-C depicts an embodiment with the adhesive sealing sheet storedin a package on the dorsal surface of the unified dressing structure,which is centrally affixed to the dressing at fabrication. FIG. 11Aillustrates a representation of the folded package embodiment of thesealing layer, which can exist over any of the MWT dressings describedherein (e.g., single layer, unidirectional wound filler or multi-layereddressing). FIG. 11B illustrates one fourth of the sealing layer 1101depicted in FIG. 11A. Element 1103 in FIG. 11A represents an MWTdressing that may be covered by the sealing layer 1101. Variousimplementations of the sealing layer 1101 may be configured to cover thedifferent embodiments of MWT dressings. The dotted lines of FIGS. 11A-Crepresent the fold lines for folding up the sealing layer 1101. Variousembodiments may be folded in different manners than that depicted in thefigures, along different fold lines than illustrated. FIG. 11C depictsan embodiment with flaps 1109 configured to overlap with the next foldedout portion of the sealing layer 1101. The overlapping flaps help toensure an airtight seal over wound areas with a convex surface, or thatare otherwise not on a flat portion of the patient's body.

The sealing layer 1101 depicted in FIG. 11A has an “iron cross”configuration, configured to fold out in four directions. FIG. 11Adepicts one of the sides in an unfolded state, while the other threesides 1107 are still in a folded state. However, in other embodimentsthe sealing layer may simply be configured as a single sheet folded inthe midline. In folded package embodiments such as those illustrated inFIGS. 11A-C, adhesive may be placed either on the entire ventralsurface, or only the peripheral aspect of the ventral surface of thesealing layer, e.g., extending inward from the edge by anywhere withinthe range of 2 to 50 cm. The dressing may be cut to size, to match thedimensions of the wound. Then the sealing layer is unfolded from itscentral location to extend beyond the edges of the dressing, and thepeel-away paper backing is removed. It is then pressed down on thedorsal surface of the dressing and then onto the skin margins. Thisaffects an airtight seal. Adhesive sealing sheets can be placed inaddition to the folded sealing layer 1101 to support and further ensurethe seal is air-tight. The adhesive layer will be very thinapproximately 0.1 to 1 mm thick, similar to Tegaderm™ or Ioban™. It mayextend out past the edges of the dressing by several inches to allow foran appropriate seal. It can be cut down to allow specific modificationto fit different types of wounds. It can have an additional reinforcingcovering that can be peeled off on the dorsal surface of the dressing toprevent wrinkling during application of the adhesive sealing layer.

FIGS. 12A-B depict embodiments having different textures for the woundfacing surface. As shown in FIG. 12A, in some embodiments the woundfacing surface of the ventral most layer of the layered dressing or thenetting and tubular components of the single layer dressing isconfigured with an abrasive surface. The abrasive surface may be made upof varying sizes from <1 to 5 mm in depth or by the mesh screen itself.The micromotion aids in the wound surface being “scrubbed” to removedead or devitalized tissue from the surface of the wound. The ventralsurface, or deep surface (e.g., facing the wound), can be constructed ofan abrasive material to apply micro-abrasion to the wound surface. Thismicro-abrasion or micro-debridement effect is accentuated by contractionof the underlying muscle in the wound bed and by interval application ofexternal positive pressure via a positive pressure module describedherein. In other embodiments, such as that shown in FIG. 12B, the woundfacing surface of the ventral most layer can be configured to have asmooth, non-stick surface. The non-stick surface is useful for placingover skin-graft sites or other reconstructed or tenuous tissue. Thenon-stick surface aids in reducing tissue tears/injury when the MWTdressing is removed. The non-stick surface layer can also be used inmore mature, less dirty wounds, as the non-stick feature tends to cutdown on pain and bleeding associated with removing NPWT dressings.

FIG. 12C depicts a unidirectional embodiment with a sponge-like ventralsurface 1212 facing the wound. This may be implemented in various in MWTembodiments by using a dressing material 1212 that has a sponge-likequality. This material may be made of a sponge type material, a gauzematerial or fiber, a polymer or other biologically inert porous andcompressible material. The depth can range from 2 mm to 2 cm based onthe depth of the wound. In such embodiments the dorsal side of thesponge-like wound filler 1212—that is, the side way from thewound—typically has a fabricated air-tight coating that, on the surfacefacing away from the dressing, adheres well to adhesive sealing sheets1214. This air-tight coating prevents fluids from rising to the surfacein the area overlying the sponge-like filler. As such, an airtight sealbetween this unidirectional dressing and the skin at the margins of thewound only requires placement of impervious adhesive sealing sheets 1214at the periphery of the dressing and onto the skin margins. Theunidirectional filler 1212 can rest directly on the wound surface orabove various embodiments disclosed in the layered dressing. Thefabrication of an air-tight seal on a single side of the wound filler,specifically a sponge-like wound filler, produces a directionality tothe dressing. Conventional wound fillers are non-directional, inasmuchas all sides have the same properties. These conventional fillersrequire a sealing layer, typically an adhesive film, to cover the entiredressing, not just the periphery. These non-directional fillers, rapidlybecome wetted while attempting to place conventional NPWT dressings.This compromises or eliminates the adhesion between the separatelyapplied sealing layer and the wound filler, which can lead to leaks anddressing failure. The air-tight seal on the dorsal surface (away fromthe wound) described herein produces a unidirectional filler. Such aunidirectional filler can only be applied in the correct direction on awound.

The one-piece unidirectional embodiment facilitates application of thedressing by providing a fabricated seal to the wound filler. This sealcan be applied in a multitude of manufacturing methods, like beingannealed to the filler or poured over as a liquid form and allowed todry. The depth of the seal may be from 0.5 mm to 5 mm in depth. Invarious embodiments the material may be a plastic, polymer, silicone, orother malleable substance to allow an airtight seal but alsoflexibility. By contrast, conventional systems are typically applied intwo separate parts. First, the conventional wound filler (sponge piecesor gauze cut to fit the wound shape) is placed into the wound, which isgenerally moist. Doing this typically causes the conventional woundfiller to become wetted upon application to the wound. This wettingimmediately degrades the adhesive potential of the dorsal surface ofconventional, non-directional wound fillers and increases the potentialfor system failure, through leakage or seal failure.

The one-piece unidirectional sponge-like wound filler dressings of thepresent embodiments incorporates either a flange or a vacuum interfacechamber into the dressing. Typically, the vacuum interface chamber orflange lies within the sealed portion of the dressing or deep to thefiller embodiments where the wound filler lies above a layered dressing.Additional tubing/conduits (e.g., irrigation tubing) for the specificembodiment of the MWT dressing pass through the air-tight sealing layerinto the sealed portion of the wound filler. This sealed passage istypically created at fabrication, (e.g., already present when thedressing is ready for clinical use), producing a unified unidirectionaldressing.

Various embodiments provide an airtight sealing layer fabricated in themanufacturing process so that the entire dorsal surface of the spongedressing or nonsponge dressing, for example the layered dressingembodiment, does not need to be covered by adhesive film type materialto be sealed—only the periphery needs to be covered by the adhesivesealing sheets to affect a seal between the dressing and the skinmargins. In some embodiments, the sealing layer may not extend to theentire periphery of the dorsal surface, leaving nondirectional (e.g.able to absorb, filter, act as a flow-path for the vacuum and/orirrigant) wound filling material at the peripheral margin. Thisembodiment is often used in wounds with large skin flaps, in which thearea of the wound is greater than the of the skin defect. Thenondirectional portions of the wound filler may be cut to match thecontours and depth of the wound. The dressing may then be placed intothe wound such that the sealing layer lies proximate the dorsum of thewound, and adhesive sealing sheets may be used to complete the seal.

An airtight sealant or adhesive-backed airtight sealing layer is appliedto the single-unit dressing, typically during the fabrication process,so that the dressing under the sealant/sealing layer is airtight. Tocomplete the airtight seal of the unidirectional dressing (for allembodiments including those with complete or partial coverage of thedorsal surface of the dressing by the sealing layer) to the wound,adhesive sheets are added to the periphery that simply tape/seal theedges of the unified unidirectional dressing to the skin at the marginsof the wound. In various implementations the system is covered on thedorsal surface by spray plastic or some airtight material to seal thedorsal surface in the manufacturing process. The airtight sealing layermade inherent to the dressing through the manufacturing process allowsfor ease of placement on the patient. One of the most difficult aspectsof the current art is obtaining an airtight seal over the piecemealplaced wound filler around a central suction tube. Conventional systemuse adhesive film sheets that can fold onto themselves duringapplication, creating folds and wrinkles which increase the risk ofleaks. By fabricating the sealing layer to the dressing, theuni-directional dressing facilitates sealing to the wound marginsinsuring an airtight seal over the dressing itself regardless of foldsor wrinkles in the adhesive sheets. Further, unlike conventionaldressings which are constructed piece-meal at application, the elementsneeded to provide the intended clinical effect are fabricated into asingle unit. This unified dressing is a substantial improvement over thecurrent art by overcoming the most common sources of failure forconventional systems.

In various embodiments the whole system is configured to be airtightwith an apron-like peripheral extension of the dorsal most layer of thedressing (the airtight sealing layer), that extends beyond thedimensions of the dressing. In these embodiments the dressing typicallylies beneath the airtight sealing layer. The airtight sealing layer isaffixed to the central portion of the dressing, maintaining thesingle-unit, unified design. The sealing layer in the apron embodimentsis significantly larger in area than the underlying dressing—(e.g. twicethe area of the underlying dressing), so that the airtight sealing layerextends beyond the dressing in all directions, for example, as shown inFIG. 1P. This sealing layer could be in a similar form to Ioban™ orTegaderm™.

In some embodiments, the sealing layer is affixed to the dressing acrossits entire shared area (e.g., the ventral side of airtight sealing layeroverlying the dorsal side of remaining dressing elements) or only“spot-welded” at points, in other embodiments, the ventral surface (sidefacing the wound) of the sealing layer is covered with adhesive, whichin turn is covered with peel-away paper backing, that is removed atdressing application. The wound filler/functional elements of thedressing and the airtight sealing layer can be individually cut to fitthe wound, prior to removing the peel-away paper backing in theembodiments with a ventral adhesive surface on the sealing layer. Thisfeature of separating the dressing and sealing layer except for acentral fixation point allows for customization of both the dressing andthe sealing layer individually but still maintain a unified dressing. Inembodiments in which the airtight sealing layer is not affixedcontinuously or at multiple points (e.g., spot welded) throughfabrication to the dorsal surface of the dressing, the dressing isseparate from the airtight sealing layer at all points, except for thecentral fixation site. This central fixation site is typically withinthe 2-6 cm diameter reinforced central area (e.g. vacuum interfacechamber) at the dorsal surface 1216 of the dressing through whichconnecting tubes enter the dressing in a sealed fashion. This airtightlinkage of tubing to dressing is typically created at fabrication, inkeeping with the unified dressing concept.

In some embodiments an adhesive-backed airtight sealing layer is foldedaway from the dressing layer in order to cut the dressing to size. Oncethe dressing is cut to the proper size and shape, the sealant layer canthen be unfolded, the peel-away paper backing removed, and the adhesivesealing layer can be affixed over the remaining portions of thedressing, and then affixed to the skin at the wound margins, thuscreating an airtight seal. Prior to this, the adhesive-backed airtightsealing layer can also be cut to fit the shape of the wound margins. Inother embodiments, the adhesive portion of the sealing layer is notpresent centrally, but only at the periphery. In an apron-likeembodiment with the apron affixed in an airtight fashion by adhesiveand/or fabrication centrally and affixed to the periphery of thedressing and normal skin margins via adhesive, which is initiallycovered with peel-off paper backing. The apron is free of the underlyingdressing at the periphery, which allows the dressing to be cut to thedimensions of the wound, without cutting the apron. The apron can alsobe cut to match the shape of the wound. The apron is typically longer inall dimensions than the dressing by at least 1 inch. This over-hang isthe surface area that will cover and stick to the skin margins, when thepeel-off paper backing is removed and the apron is sealed to the patientto affect an airtight seal. Other apron-like embodiments, do not haveadhesive on the ventral side, but a tacky substance on the dorsal side.This is intended to provide a better surface for applying adhesivesealing sheets to seal the dressing to the wound margins.

FIG. 13A depicts an embodiment of a basic MWT dressing that uses both avacuum tubing system 1301 and a separate, dedicated irrigation tubingsystem 1303. In the embodiment of FIG. 13A the individual perforatedtubes of the tubing system are interconnected in a web-like pattern.There are two completely separate in-flow and out-flow circuits aredepicted. The portions of the in-flow and out-flow circuits closest tothe wound surface are tubing systems. The vacuum tubing system 1301 liesdorsal to the irrigation tubing system 1303. The wound pressure sensor1307 is positioned directly at the wound surface.

The embodiment of FIG. 13A features a dual tubing system in which thevacuum tube circuitry 1301 is independent of the irrigation tubecircuitry 1303. In the embodiment of FIG. 13A the vacuum interfacechamber and irrigation tubing system are independent and notcoplanar—that is, the vacuum interface chamber 1305 lies dorsal to theirrigation tubing system 1303, which lies on the surface of the wound.In yet other embodiments, for example, the embodiment depicted in FIG.13C, the vacuum lines 1321 and irrigation lines 1323 are co-locatedwithin the same layer. In some embodiments the vacuum and irrigationlines are strictly coplanar, within the same plane. But in otherembodiments they may have non-planar connections, that is, crossing overeach other to achieve an even dispersal of irrigant delivery and vacuumevacuation, as shown by the dotted line 1325 in FIG. 13C.

The design of the tubing systems ultimately requires the irrigant totravel across the wound surface to reach the vacuum outflow. The path ofleast resistance, which is ultimately the path in which the fluid willtravel, crosses over the wound. By fixedly separating the areas fordelivery and removal of fluid, the fluid is required to travel over thewound aiding in irrigation and cleansing of the wound. This dual tubingconcept is novel in design and function. Other embodiments feature asingle tubing network, rather than a dual tubing network.

FIG. 13B depicts an embodiment of a single layer dressing in which thein-flow circuit is the only side with a tubing system 1306. In thisembodiment vacuum reaches the sealed dressing through the vacuuminterface chamber 1305, without a vacuum tubing network.

Returning to FIG. 13A, in various embodiments the irrigant and vacuumtubing systems are individually controlled or controlled in groups, soas to activate the whole dressing or selected portions of the irrigantand vacuum tubing systems. In some embodiments the irrigant tubingsystem over the whole wound or a portion of the wound may be turned onwhile the vacuum tubing system over the whole wound or a portion of thewound are also turned on. The remaining irrigant and vacuum tubes may beselectively turned off. In this way, a portion of the vacuum circuit canbe turned on while another portion of the irrigant is operating so as todirect the flow of fluids across the wound from the irrigant lines tothe vacuum lines. This allows the caregiver to tailor the rate ofirrigation and vacuum for those portions of the wound needing suchattention.

In accordance with various embodiments of MWT, irrigation tubing systemmay be configured to lie proximate of the wound surface (e.g., within 1mm, or within 1 layer of netting). This can be seen in FIG. 1C in whichthe irrigation tubing is positioned sandwiched between layeringmaterial, which is netting, mesh or a thin perforated film. In thisconfiguration, the irrigation tubing system is the ventral functionalelement of a layered basic MWT dressing. The irrigation tubing systemdelivers an irrigant which can be sterile or potable water or othercleansing or adjuvant therapeutic fluids or gases. The irrigant can bedelivered under pressure either from an irrigation pumping system orthrough reverse pulse lavage, in which bursts of vacuum are applied to aone-way valve controlled, gravity fed irrigant source. In someembodiments the irrigation tubing has a port configured to receiveinjections of therapeutic fluid dosages. The layered dressing designaids in maintaining the spatial relationship between the irrigationtubing and the vacuum tubing or vacuum interface chamber/flange, suchthat the irrigation system is held close to the wound surface withperforations in the tubing of the irrigation system directed towards thewound. By fixedly maintaining the position of the tubing, the spatialrelationship between irrigant delivery and removal is maintained. Thereby providing the greatest assurance that irrigant passes over thesurface of the wound, assisting in cleansing of devitalized tissue andbio-burden from the wound bed.

In some embodiments there are no perforations in the irrigation tubingother than at the terminal extent of each limb of the irrigation tubingsystem when it is arranged in a radial pattern, which acts to deliverthe irrigant to the periphery of the wound, allowing the irrigant totravel across the wound surface as it is suctioned from the wound viathe centrally located vacuum interface or separate vacuum tubing system.These combined design features mean that irrigation will be directlyapplied at or near the wound surface where it can cleanse the wound andreduce fibrin slough and biofilm formation. Since, in variousembodiments, the irrigation tubing system is completely separate fromthe vacuum source, these two functions can be paired to optimallyirrigate the wound surface while helping to prevent the formation ofpooled fluid. Likewise, the reverse pulse lavage mode, can simplify thesystem, by eliminating a need for a positive pressure irrigant pump. Acontrol valve may be placed in the irrigation tubing circuit, to allowflow in response to negative pressure being applied at the level of thedressing. Distal to this control valve is a crimp, or similar device,configured to keep the irrigation line closed so that irrigation is onlyprovided when intended, e.g., when the crimp is removed to open theline. The control valve and/or crimp can be operated manually orelectronically. In embodiments with electronically operated distalcontrol valves and/or crimps, the EVR typically regulates the setting ofthese control features. Different modes of therapy that call forspecific sequencing of vacuum and irrigation, can be programmed into theEVR during manufacturing or custom modes can be programmed by theend-user.

In some embodiments, the irrigation and vacuum connection tubing haveaccess ports proximal to the tubing connection point with the basicdressing, allowing connection to a separate dressing or wound site.Y-shaped tubing with slip-fit connectors, or other types of connectors,can be connected to the branched portion of tubing to make a multitudeof splits in the primary vacuum and irrigation tubing, to allow coverageof multiple wounds.

Another embodiment allows the device to intermix a gas into theirrigation line. By alternating fluid and gas, the suction driving thepassage of irrigation allows gas to “clear the system” and prevent fluidpooling or back flow when the dressing is not being suctioned, e.g., asdescribed in FIG. 3A. The vacuum burst is applied, for the first half ofthe burst time period it pulls fluid across the wound, the second halfof the burst it pulls a gas across the wound. This embodiment allows theirrigant to be pulled across the wound and removed from the dressingpreventing fluid pooling and seal disruption.

The novel dual-tubing vacuum/irrigation system of the variousembodiments disclosed herein helps to prevent pooling and effectivelyreplicates the low-pressure lavage techniques which have been provenbeneficial in the treatment of wounds. Unlike operative lavage, whichtypically can only be performed once per day at most and requires a tripto the operating room, the irrigation therapy of various MWT embodimentscan be performed as many times per day as the provider prefers, orcontinuously.

Various embodiments include a biocompatible polymer/plastic netting,mesh or thin perforated film. Some layers may be impregnated withantimicrobial agents, like antibiotics or silver or with bioactivemolecules (e.g. cytokines in the transforming growth factor-betafamily). Others may use one or more bioabsorbable netting, mesh or thinperforated film layers which can have varying absorption rates perlayer. These layers can vary in thickness from 1 mm to 1 cm based on thedesired time of absorption. Possible materials are Polyhydroxyalkanoate(PHA), Poly(lactic acid) (PLA), Polycaprolactone (PCL), Polyesteramide(PEA), Aromatic copolyesters (e.g. PBAT), Aliphatic copolyesters (e.g.PBSA), or Polyglycolide or Polyglycolic acid (PGA). The use ofbioabsorbable layering or wound filling material is well suited fortissue engineering applications and/or extended duration use. Likewise,at least one embodiment uses all bioabsorbable layering material in thelayers of the dressing, such that as the wound dimensions are closed,specifically with the assistances of the wound approximating devicemodule described herein, the netting, mesh or thin perforated film layercan be absorbed, leaving only the vacuum/irrigation system functionalelements and in some embodiments additional monitors/adjuvants, whichwill fold on themselves. Further, while the netting, mesh or thinperforated film based dressing is designed to overcome the flaw ofconventional dressings which can leave dressing debris in the wound bedat changes, the bioabsorbable construction of some or all of thenetting, mesh or thin perforated film layers can further overcome thisflaw. If a piece of the netting, mesh or thin perforated film is leftbehind, it will harmlessly absorb, similar to absorbable sutures in awound.

Various embodiments of the netting, mesh or thin perforated film layercan be composed of completely bioabsorbable materials that can beimpregnated with antimicrobially active agents (e.g., antibiotic powdersor the like) and biologically active agents (e.g., pluripotent cell,TGF-B, BMPs, or the like). A “bioabsorbable material” eventuallydissolves and is absorbed by the body. The interface can act as abioactive scaffold that draws healing cells into the matrix to createlayers of new tissue over the exposed depth of the wound. Theseembodiments may be best suited for open wounds over-lying expose bone,tendon or other vital extremity tissue, which needs direct soft tissuecoverage prior to skin grafting or allowing the wound to be treated in atraditional fashion with cotton dressings to secondary intent. Inanother embodiment, the deepest layer of the dressing can be composed ofa biologically well tolerated material, that is smooth on its ventralsurface. During manufacturing cultured tissue or allogenic tissue can beapproximated to this ventral layer so as to stay removably affixedduring the process of applying the dressing to the wound. The tissuelayer is typically collagen-based, to serve as a substrate for localhost tissue in-growth. It may be impregnated with cultured cells orbiologically active agents, like cytokines. When impregnated withbiologically active agents, the concentration of the agent can betitrated geometrically, so as to establish a concentration gradient thathelps to select and direct host tissue response. In some embodiments,the tissue layer can be composite tissue (e.g., full or partialthickness allogenic skin). The smooth ventral most non-absorbable layerof the MWT dressing, serves to allow safe separation of the dressingfrom the tissue layer, after a prescribed period of MWT care to thewound, typically 5-7 days. By this construction, the newintegrated/transplanted tissue layer, will remain affixed to the woundbed, to which it is or will become biologically incorporated.

A biological dressing such as allograft skin or collagen matrix may beattached to the ventral aspect of the dressing creating a composite MWTdressing. A composite dressing with a human tissue or tissue substratecan be affixed to the composite dressing to aid in avoiding the need forautograft. This composite dressing can, in some embodiments, be a secondphase dressing made to allow for wound coverage without the need forautogenic grafting. Once a stable clean wound bed has been obtained, asecond composite wound coverage dressing can be applied. This compositewound coverage dressing may have a biological substance on the ventralside of the dressing. In some embodiments the biological layer may beremovably affixed to the dressing—e.g., a non-biological MWTdressing—via a biodegradable fixative or by simple fluid adhesion. Thefixative used to hold the layers together may be configured to degradeover various predefined ranges of time, e.g., from a period of hours todays, or even weeks in some situations. The NPWT tends to compress thebiologic substance to the wound surface increasing the likelihood ofincorporation. Once the biologic layer has been incorporated thedressing is removed. The fixative has degraded leaving the dressingseparate from the biologic layer that is now attached to the woundsurface creating a covered wound without autogenic grafting.

The netting, mesh or thin perforated film can be configured to be placedin multiple layers in order to produce the desired thickness. Dependingupon the implementation, the layers can be laid upon each other eitherin parallel, perpendicular to each other, or with small amounts ofangular rotation between layers, e.g., as shown in FIG. 1F. While thislayering can be performed in-situ, the typical embodiment has a setnumber of layers fused or otherwise permanently affixed to interveningfunctional elements or spacers, and through these connections, beindirectly affixed to each other, so that the dressing is a single unit.In some embodiments the fused layers are configured such that one ormore of the outside layers can be removed in order to vary the thicknessof the layer assembly. The various layers can be separated by functionalelements of the dressing and/or spacers of a predetermined width.Spacers and functional elements allow for the dressing to be constructedto an ideal thickness, while maintaining pliability (to follow theirregular surface of the wound) and collapsibility (to allow theelements contained in the layered, single layer or unidirectional woundfiller dressing, to collapse on themselves to facilitate, rather thanhinder, the device assisted and biologically inherent process of woundapproximation. In lieu of spacers, additional monitors (like pressure,pH, O2, NIRS sensors or camera) can be placed in specific locations tomonitor the health of the wound. Typically, the dorsal most and ventralmost layering material has special characteristics to improvefunctionality of the dressing. The dorsal most layer typically has anair-tight sealing layer applied at fabrication to its dorsal surface.The ventral most layer typically has an abrasive ventral surface, thatcontributes to micro-abrasion of the wound bed. In some embodiments, theventral most layer may be smooth or non-stick, to prevent adhesion tothe underlying host tissue. The size of the open spaces or pores in thenetting, mesh or thin perforated film, can be adjusted throughmanufacturing to encourage or discourage specific biological hostresponse, such as tissue in-growth.

The netting, mesh or thin perforated film provides a plurality of flowpaths for fluid suctioned from the wound and irrigation to the wound.Between the layers, plastic material/strips can by placed as spacers,that maintain the plurality of flow paths, while adding substance, depthand form to the dressing material, such that it can hold its shape andmore easily be cut to size, when it is customized to an individualwound.

At least some embodiments of the system are suitable for serving as abridge dressing, to be used at the first or early surgical debridementprocedures for particularly dirty or otherwise challenging wounds, inwhich serial surgical irrigation and debridement procedures are deemednecessary by the treating physician. The bridge dressing embodiment is astripped down version of the multi-functional MWT dressing, possessingin its most simplest form only a vacuum source (vacuum interface ortubing system with or without accessory tubing), with or without a woundpressure sensor. This novel dressing is intended to serve as a bridgebetween presentation and gross surgical decontamination. The layers ofnetting, mesh or thin perforated film in this bridge dressing may or maynot be separated by plastic spacers or functional elements. The dorsalsurface may or may not be sealed. When it is not sealed, the bridgedressing is mutlidirectional, in that it can apply vacuum and/orirrigation in all directions. The wound side surface may or may not beabrasive.

This bridge dressing is often used for shorter durations of time (e.g.,24-72 hours), in situations where the surgeon or care provider feels thewound requires serial sharp debridement and irrigation. Such care may berendered during in-office care, hospital settings or the operating room,prior to achieving effective gross surgical decontamination. At thatpoint, the multi-functional MWT embodiments are typically implementeduntil the wound is ready for delayed primary closure or other form ofdefinitive treatment. In some cases, these simplified bridge dressingswill be the sole dressing used for 1401 the extent of MWT therapy, oftenin smaller, less complicated wounds.

FIG. 14 depicts an embodiment with an accessory tube 1401. Variousembodiments are configured with one or more accessory tube(s) 1401 thatextend from a central point off of, in addition to, or in lieu of, avacuum interface chamber/flange or an irrigation tubing system. Theaccessory tube(s) 1401 may be used to convey only vacuum, only irrigant,or multiple accessory tubes 1401 may be used to convey both vacuum andirrigation. In some implementations the accessory tube(s) 1401 aresimply straight tubes, while in other implementations the accessorytube(s) 1401 are configured in a figure-eight fashion, in which oneflow-path is dedicated to vacuum and one flow-path is dedicated toirrigation, as shown in FIG. 14, or like type of design. Accessory tubesserve two primary functions, (1) conduits to bridge dressings or (2)independent functional elements (e.g., vacuum/irrigation flow paths)that can be directed into tract-like areas of the wound or partially orcompletely surgically closed (e.g., sutured) areas of the wound. Whenacting as an independent functional element, the accessory tube can havean ending portion that is flat, round or another shape conducive todraining or delivering irrigant to a portion of the wound. An additionalconfiguration includes multiple loops of this tubing with a centralcommunication point that produce a more bulbous effect, to fill cavitarylesions, e.g., as shown in FIG. 4.

The accessory tube(s) 1401 of FIG. 14 are typically of sufficient lengthto be laid into elongated, narrow tracts within the depths of the wound(e.g., gunshot tracts), that are not well treated by current forms ofNPWT dressing. Accessory tube(s) 1401 aid in preventing narrowed, moresuperficial areas of the tract from closing, leaving a dead, potentiallydirty, space in the depth of the wound that is not in communication withthe vacuum source. In one common use, the accessory tubing 1401 isconfigured as a single function tube interconnected with the vacuumcircuit. The system is configurable so that one or more accessory tubescan branch off the wound interface chamber/flange, delivering directedvacuum to tract-like wounds or to serve as a conduit to accessorydressings.

In another additional embodiment, the accessory tube is the singleflow-path between the regulated vacuum source and the patient. In thisinstance, the accessory tube typically looks like a standard closedsurgical drainage tube (e.g., a 10 French Jackson-Pratt drainage tube),and the draining end of the tube is placed into the wound or operatedportion of the patient, for instance the knee joint after a kneereconstruction, and the conduit end of the tube connects to the vacuumconnection tube, which connects to the collection canister andEVR/vacuum source. This embodiment represents an automated version ofthe common closed surgical drain, which typically applies suctionthrough deforming the shape of the collection canister, and allowingrecoil of a spring (HemoVac) or the collection bulb itself(Jackson-Pratt drain) to produce the negative pressure in the closedsystem. A clinical benefit of the automated closed surgical drainagetechnique described herein, is that the flow can be measuredautomatically using a flow measurement device and downloaded directlyfrom the EVR to the electronic medical record. Alarms or feedback can beprogrammed in the EVR that alert the provider when certain total volumesor volume rates are exceeded. Further the level of vacuum can bestrictly regulated with this technique, versus the recoil techniquesmentioned. Additionally, the drain may have a one-way valve to preventback flow at the junction of the drain and vacuum connection tubing.

The accessory tube(s) 1401 may also serve as conduits for specialbi-directional versions of the netting, mesh or thin perforated filmdressing that can be placed into deeper planes of the wound. Theseaccessory dressings are constructed as simple bridge dressings asdescribed above. They can have a radial (e.g., centripetal or Christmastree like) or spider-web tubing system with or without nettinginterspaced between the limbs of the tubing system, that can directvacuum flow alone or with a dedicated irrigation tubing system to thesedeeper, undulating areas, where two-chamber conditions are most likelyto form, in which small pockets of the wound can self-seal and the newclosed space can be separated from the negative pressure applied to thelarger portion of the wound. In the accessory dressing, a radial orspider-web vacuum tubing system and/or plastic spacers will typically besecured (“sandwiched”) between the layers of the dressing, with orwithout additional layers separated by plastic strips, one or moresupport members, or irrigation tubing. Typically, neither surface wouldbe sealed (e.g., bi-directional), but rather, would be available tosuction wound fluid and deliver irrigant, with or without roughening ofthe surface in all directions.

A potential additional use of the accessory tube and bridge dressing isto treat less severe satellite injuries from a major wound that is beingtreated with a multi-functional MWT dressing. In this situationaccessory tubing connects the vacuum interface of the primarymulti-functional MWT dressing via an airtight port on its dorsal surfacewith the bridge dressing. A similar accessory tube can be removablyconnected the irrigation connection tubing to an irrigation layer in thebridge dressing, if irrigation were to be provided, as well. Theaccessory tubes, are dorsal or outside of the sealing layer of theprimary MWT dressing. Ports just dorsal to the seal for both vacuum andirrigation allow for a series of dressings to be regulated by a singleEVR, producing serial dressing therapy. Cross contamination of woundsmay be prevented through the use of the one way valves that preventbackflow, e.g., as shown in FIG. 5A. One specific embodiment of thisprimary wound/satellite wound dressing would be a fasciotomy specificdressing, which has a primary MWT dressing that covers the larger openfasciotomy wound, on the lateral leg for instance, while thecontralateral fasciotomy wound is closed, typically the medial side ofthe leg. This special embodiment, has a standard multi-function MWTprimary dressing, with an accessory tube that ends in a configurationthat is most similar to a long flat drain (e.g., similar to a 10 FrenchJackson-Pratt flat drain). The flat drain appendage is placed in thecontralateral wound, and that wound is closed over the drain. Thisprovides active, regulated and metered drainage of the freshly closedwound, while the primary wound is being prepared for closure or coverageunder the multi-functional MWT dressing.

In cases, where it is desired to route irrigation and suction to deeperplanes of the wound the accessory tubes 1401 can be configured toinclude tubes for both the irrigation and vacuum functions. For example,the accessory tube(s) 1401 may be configured in a figure eightdesign—that is, two separate tubes fused together to provide separateirrigation and vacuum lines. The two lines may extend from a centraltubing connection point out about 6 cm or longer. In some situations,perforations in each tube 1401 are configured to point away from eachother, to maximize the distance irrigation must travel to reach thevacuum out-flow tube. In one implementation the irrigation side may havefluid passage holes that do not start until 2 cm or more distal to thecentral connection point. In similar implementations, the vacuum linesmay only have perforations more centrally located, so as to prescribe aflow-path from peripheral to central across the wound surface. In somesituations the full length of the tube may be used, as is, to fill deeptracts. In other situations the tube can have no perforations (e.g. akinto conduit tubing) in its walls and be cut to the length needed for thewound, and connected to accessory dressings possessing separate vacuumtubing and irrigation tubing layers.

The accessory tube(s) 1401 may be configured to slip over, or fit on to,or by some other mechanism fluidically connect to short segments oftubing from the irrigation and vacuum system in the accessory dressings.In this way the accessory tube(s) 1401 connect to accessory dressingsmaintaining dedicated fluidic flow paths for vacuum and irrigation fromwound surface to the collection canister or irrigation source (FIG. 5A).Bi-directional accessory dressings can be placed in deep planes, largerthan what is best addressed with only a simple figure-eight shaped tube,thus extending MWT function to all aspects of these complex wounds. Thisis particularly useful in the treatment of large combat wounds ortraumatic amputation stumps, in which multiple potential dead spacesoccur between large flaps of muscles. One current method is to placesponge or gauze dressing into these blind, deep spaces, which does notguarantee full coverage of the space, but most importantly can lead tonot only micro-debris from the sponge or gauze, but macro-debris, fromentire pieces of the conventional dressing material being left in thesespaces at serial dressings.

Dressings that do not use conventional wound filler materials in someembodiments may be composed of tubing that may or may not be interspaced with netting material, in which the wound facing ventral surfacehas an abrasive surface, that can micro-abrade the wound and assist inmechanical debrided. The non-wound filler dressing may be configured tohave a netting material or thin perforated film that connects betweenlimbs of the single layer tubing dressing to present one single planarsurface. The netting portion may also have an abrasive surface againstthe wound to provide a debridement function, e.g., as shown in FIG. 1L.In layered dressing embodiments, the ventral most layering material canalso have an abrasive ventral surface to produce a micro-abrasioneffect.

FIG. 15 depicts an embodiment of a vacuum and/or irrigation tubingsystem configured with netting or thin perforated film 1501 disposedbetween the sections of tubing 1503 in the vacuum or irrigant tubingsystem. In some embodiments the netting or thin perforated film 1501spanning between the tube components 803 is composed of a material thatis not susceptible to decomposition, for example, a metal, plastic orother synthetic material that does not break down in the presence offluids or other wound conditions.

In other embodiments the netting 1501 spanning between the tubecomponents 1503 is composed of biodegradable, hypoallergenic materials.In this way, if any such netting material becomes trapped in the woundgranulation tissue, it will not be a permanent foreign object that couldlead to chronic inflammation or infection. In some embodiments thenetting layer 1500 can also be composed of nonstick, low coefficient offriction materials. The smooth/nonstick surface is ideal for beingplaced over grafts, bioengineered tissue or other tenuous tissues, toreduce the shear stress during wear and the adhesion stress duringremoval.

NPWT has been used over top of skin grafts to compress the skin graftdown to the recipient bed while also removing potential hematomas thatlimit graft take. Some embodiments feature a dual-sided layeringmaterial with one side comprising an adhesive and the other sidecomprising a nonstick, low coefficient of friction material. Thisadd-on/modular nonstick layer may be placed on the ventral side of abasic MWT dressing to convert an abrasive surface to a slick, non-sticksurface. The nonstick side of the special layering material now becomesthe ventral surface, nearest the wound, of the unified basic MWTdressing. The nonstick, low coefficient of friction aspect of thelayering material facing the wound tends to reduce shearing stress andadhesion of the dressing to the skin graft or underlying tissue. Someconfigurations feature two layers interspaced by springs, bearings orlubricant that prevent or attenuate shear forces applied to the dorsalaspect of the dressing from being transmitted to the skin-graftrecipient site or wound bed. In some embodiments, a separate nonsticklayer of low coefficient of friction material, can be placed on the skingraft, allowing a gliding action between this layer and the dressing.Skin graft dressing may be a separate special dressing. In alternateembodiments, the ventral most layer of the unified layered dressing isnot abrasive, but rather, is configured to have a slick or nonstickventral surface to reduce shear and adhesion forces over skin grafts.

A complete MWT wound care system tends to extend the useful wear time ofthe dressing. Conventional NPWT dressings must be changed every 24-72hours. Unfortunately, this is not sufficient time for many wounds toheal to the point of being ready for definitive soft tissue management.This is a weakness of conventional systems which demand the frequentdressing change schedule, an exercise that is costly in both suppliesand labor, and quite painful to the patient. Frequent dressing changesalso expose the wound to potential nosocomial pathogens which can bemore virulent and/or difficult to treat than the microbes whichinitially inoculate a wound at time of injury.

One advantage of an MWT wound care system, as opposed to conventionalNPWT devices, is that various embodiments of the presently disclosed MWTwound care system can be applied after the first or second (or more)surgical irrigation and debridement procedures (depending oncontamination level) and left in place with a single application untilthe wound is ready for definitive soft tissue management. This timeframe is typically greater than the 24-72 hour time limit for changingconventional NPWT system dressings. In order for the wound care systemto extend the wear time of a dressing, the various embodiments disclosedherein provide an improved ability to evaluate the underlying wound.

In conventional devices the dressing has little or no structuralintegrity as they consist of piecemeal placed soft sponges or gauze thatadheres to the wound and allows for tissue in growth. The dressingtherefore has to be removed within 24 to 72 hours to prevent significantin growth. The current MWT design allows for motion between the dressingand the wound surface. This motion can accentuate the micro-abrasioneffect of the abrasive ventral layer. This motion is made possible bythe structural integrity of the dressing which in some embodimentsprevents the dressing from completely conforming to the wound. Thisdressing can be staple or otherwise be removably, rigidly affixed to theskin margins. The motion created produces a gentle grating of tissueinstead of allowing tissue in growth. Motion of the muscles as well aspatient movement encourage wound dressing motion. Additionally, thepositive pressure bladder module and the wound approximator module willboth encourage small amounts of motion along the wound surface whichshould reduce or prevent tissue in growth. The inherent structuralintegrity of this dressing allows the dressing to serve as a fixationpoint in additional to its role as a maintainer of the specified spatialrelationships of the functional elements of the system contained in thedressing.

One significant weakness of conventional designs is that the woundfiller is black or otherwise opaque material. When these conventionaldressings are in place they completely obscure the underlying wound bed.This makes it difficult to diagnose the underlying wound. Further meansfor evaluating the health of the wound may need to be provided to thephysician and/or wound care specialist over the course of the extendedwound dressing wear time, to allow for early identification ofinfectious complication and/or the appropriate time to end MWT andprogress to the definitive soft tissue management procedure. In someembodiments of the MWT dressing, a translucent window or windows isincorporated into the dressing, full thickness to afford directvisualization of the wound bed. In general, the netting, mesh or thinperforated film and functional elements of the MWT dressing are made ofclear or translucent materials, to afford some visual understanding ofthe appearance of the wound bed.

In various embodiments the spaces between tubing in the web-like patternare connected by an impermeable netting or thin perforated film that istranslucent or transparent, allowing direct visual assessment of thewound. Some embodiments may have a clear window in the dressing thatallows improved visualization of the wound surface. In someimplementations the vacuum connection tubing has a port, typically justproximal of the tubing connection point/vacuum interface that allows foraseptic sampling of the wound fluid exudate. Alternatively, sampling canoccur at the port used for accessory tubes that connect island bridgedressings, when one EVR is used to programmatically care for severalwounds, as depicted in FIG. 5A.

Direct visual assessment of the wound is a potential benefit of this MWTsystem. It is made possible through several possible means in the systemdescribed herein. Transparent construction, allows viewing the woundthrough clear portions or “windows”. Additionally, a camera or tunnelsor channels to place a camera or scope through to visualize the woundcan be offered in specialized embodiments of the dressing.

FIG. 16 depicts an embodiment with multiple pressure sensors. Suchexamples of available monitors are the Tekscan thin film contactpressure sensors and various versions of flat ambient pressure sensors.As the suction is applied, the dressing is compressed to the wound. If aleak occurs, the suction and therefore the contact pressure are reducedin that area. A decrease in pressure in certain areas can be sensed bythe flat contact sensors. The location of the sensor can be identifiedby the EVR due to the spatial relationship maintained by the unifieddressing design. The sensors can be numbered, color coded or otherwisemarked to allow identification of the area where less pressure isoccurring therefore identifying the leak or the location of the leak onthe dressing. Similarly, sensors of ambient pressure can be used todirectly measure the magnitude of negative pressure at or near the woundsurface in multiple locations. Regional differences in ambient negativepressure within the sealed dressing and at the level of the EVR can bedetected to identify leaks and their location. The use of multiple wound(at or near the surface) pressure sensors 1601 aids in detectingdirectionality of an air leak and/or dead spots, which are places wherevacuum and/or irrigation is not reaching a segment of the wound surface.Multiple wound pressure sensors 1601 facilitates adjustment of thedevice for maximum effectiveness, rather than carrying on with one ormore undetected leaks. Leakage is the most common system failure inconventional NPWT embodiments, detecting leaks is a key advantage forany system using NPWT. Providing directionality of the leak is asubstantial advantage over conventional art, as it directs the providerto the area of the leak, so that additional adhesive sealing sheets canbe added to eliminate the leak. A display screen may be configured toshow an alarm condition in response to one or more of the sensors 1601detecting reduced pressure gradient(s). The sensors 1601 can be numberedor color coded for ease of identification within the dressing therebyidentifying where the leak has occurred.

Various embodiments include an alarm in communication with the sensors1601. The alarm may be built into the functionality of programmableelectronic vacuum regulator (EVR) 107 of FIG. 1A, or may be astand-alone unit. In some courses of treatment it is important that thevacuum source be maintained in communication with the wound so as tocontinually drain fluid off the wound and into a canister. Variousembodiments provide an alarm signal that indicates a situation wherematerial is blocking fluidic communication between the wound surface andthe collection canister. The term “fluidic communication” in thiscontext means that there is a pathway that liquid and gas can traverse.For example, fluidic communication exists from the wound surface to thecollection canister if there is a pathway through which fluids cantravel from a wound through a dressing into a tube and to the vacuumcollection canister. A blockage eliminates the fluidic communication, atleast temporarily, preventing fluids and gas from passing through thedevice. In some embodiments in which there is a dual (vacuum andirrigation) tubing system, the first response to a blockage alarm is toswitch the vacuum source from the vacuum tubing system over to theirrigation tubing system. In some embodiments this may be done byunplugging the tubes (e.g., at their connectors or other joints in thetubes) and switching them around, while other embodiments feature avalve for this purpose. In this way, the irrigation lines serve as abackup to the vacuum lines, in the event of vacuum line blockage oranother failure condition. Switching between the lines can be performedeither automatically in response to sensing a condition, or manually inresponse to an alarm or other indication of blockage. The switchingbetween vacuum and irrigant networks can also be performed automaticallywith a manual override. Clamps or valves in certain embodiments may beused to prevent the possibility of back-flow in the situation where theirrigation line is used as a back-up vacuum line. Additionally, portswithin the dressing and/or tubing can be placed that allow for the linesto be flushed similar to intravenous tubing used in the hospitalsetting, for example, as per accessory port 123 of FIG. 1C. The line canbe crimped on one side and flushed with a high pressure aliquot of fluidto force any material blocking the line away from the wound along thevacuum flowpath in the connection tubing to clear the blockage.Additionally, a thin firm rod can be inserted through the port tomechanically clear blockages similar to a stylet in a spinal needle.

Various embodiments include a sensor, often termed a flow meter,configured to record the volume and rate of fluids suctioned from thedressing system to the collection canister as a useful improvement. Theflow meter may be built into the functionality of programmableelectronic vacuum regulator (EVR) 107 of FIG. 1A, or may be astand-alone unit. The flow meter provides the ability to automaticallyrecord one of the most important metrics related to devices used todrain areas of the body, namely, volume suctioned in a period of time.Likewise, a flow meter allows for the system to be set to alarm in theevent the device exceeds a predefined flow threshold. This threshold canbe algorithmically (pre-programmed response) adjusted by the EVR toaccount for fluid that is irrigated, in a MWT dressing that is applyingirrigation. The flow alarm process may trigger cessation of vacuum, toimmediately stop the facilitated exsanguination that occurs in thesetting of an actively running NPWT device during a major bleedingevent. When irrigant is to be used, the predetermined amount of irrigantis programmed into the monitoring system so a flow alarm does not sound,as the irrigant is collected at a flow rate, which may be substantiallyhigher than predicted for normal suctioning of exudate from the woundsurface. For example, if one liter of irrigant is to be used to irrigatethe wound, a 1 liter button (or means to enter the data through akeyboard or similar) can be selected on the EVR. Alternatively, theduration of irrigation can be set (e.g., 30 minutes). Therefore, thespecified volume or duration of irrigation is not misinterpreted as asentinel bleeding event triggering a flow alarm. This ability to monitorand receive both input and produce programmable outputs is one of theelements of the “smart dressing” concept made possible through the MWTsystem described herein.

Various embodiments are configured with the capability for other typesof monitoring. For example, some embodiments are configured toincorporate one or more of a Near-Infrared Spectroscopy (NIRS) sensor, apH sensor, and/or temperature probe into tubular dressing system. Suchembodiments are configured to receive the monitor, camera, sensor orother probe to monitor the health of the wound surface. The data orimages from these probes can be recorded/displayed on the EVR or theprimary monitor or communicated via a wired connection or wirelessly tothe EVR or primary monitor.

In certain embodiments, a camera is incorporated in the dressing or aport is placed in the dressing to allow a camera to image the woundsurface directly. This camera can transfer information to the EVR forstorage by wire or wirelessly. This provides further means formonitoring the wound. These monitors communicate data to the EVR bywired connections or wireless links (e.g., Bluetooth or Radio FrequencyIDentification (RFID)).

Various embodiments are configured to include an advanced electronicvacuum regulator (EVR), for example, the EVR 107 of FIG. 1A. This devicemeasures flow, output and pressure at the canister and receives,interprets and responds to these monitors as well as monitors positionedin or on the MWT dressing. The enhanced monitoring ensures reliable andconsistent therapy that can be safely applied for longer periods oftime. Since the tubing is a closed system, measuring pressure at thecollection canister represents vacuum entered into the system, whilepressure sensing proximate to the wound surface measures vacuum reachingthe wound. Under ideal circumstances these two measurements should beequal in a closed system. However, in practice blockages of the tubingsystem or dressing/wound filler, or failures in the system seal (leaks)can lead to differences between the pressure measurement at the canisterand the pressure measurement proximate the wound.

Various embodiments may use different configurations of wound pressuresensors positioned in a number of locations. For example, someimplementations use one pressure sensor positioned proximate the wound(e.g., wound pressure sensor 119 of FIG. 1C), that is, between the wounddressing and the surface of the wound or separated from the woundsurface by a single layer of netting, mesh or thin perforated film.Other embodiments use two or more wound pressure sensors (e.g., pressuresensors 1601 of FIG. 16), also located at or near the wound surface. Theone or more pressure sensors are configured to communicate directly bywire, mated with the vacuum/irrigation tubing to the EVR, or cantransmit wirelessly to the EVR, using wireless technology, e.g.,Bluetooth, RFID, or the like. In one enhanced embodiment four or moresensors are positioned in a grid or at the four compass points of thedressing, to provide insight as to the location and/or direction that aleak probably may be occurring.

The electronic vacuum regulator (EVR) can be configured to either usewall suction or a portable vacuum source. Various configurations aremodular to allow for quick connection to either source of vacuum.Various embodiments feature an internal back-up vacuum motor andrechargeable power supply, in order to bridge any temporary outages orto support short trips, away from the primary wall suction vacuum source(e.g., bathroom, operating room, recovery room). Various implementationsare small enough to fit into a Pyxis or Omni-Cell logistical maintenancemachine. Unlike conventional NPWT systems, various embodiments disclosedherein are configured so one can readily separate the vacuum regulatorfrom the vacuum source, thus providing flexibility to respond tospecific, special situations that are not possible when the regulatorand vacuum source are married in a single device. Separating vacuumregulation from the vacuum source answers an unmet military (andcivilian) need, which is the ability to manage two or more wounds with anegative pressure wound dressing on the same patient at two or moredifferent levels of vacuum (e.g., full dose for an open wound andpartial strength for a skin graft site). This can be accomplished by thenovel design described herein, which separates the vacuum regulationlocation from the vacuum generation location. For certain specificindications (for instance military medical transport flights),multi-channel versions of the portable vacuum source can exist, thathave multiple or a single vacuum pump, but multiple ports that accessthe vacuum and that can be individually regulated to treat differentwounds on the same or different patients. The effluent can be collectedin a single or individualized collection canister(s) inherent to thedevice. The collection canister can be rigid (e.g., a standard vacuumcanister) or collapsible, with or without an odor reducing and/orgelling agent added to the canister.

Turning again to FIG. 5B, this figure depicts a flow diagram thatillustrates two general means for regulating vacuum and managingmultiple MWT dressings over multiple wounds on a single patient. First,an accessory fixture can be applied to the wall or portable vacuumsource. This will serve as a splitter, which takes the single vacuumsource, and provides two or more ports for individual standard EVRunits, that allow each wound to be regulated at a specific pressure.Conversely, a special EVR, that connects to a single standard wall orportable vacuum port can possess two or more ports with independentdigital regulation of each port. The single EVR with multiple vacuumports embodiment, allows for a port to remain available for routinehospital suction needs, like suctioning an airway. In this way, themulti-port embodiment of the EVR would have at least one port that couldserve simply as the vacuum regulator for therapeutic suction. These twooptions are not mutually exclusive.

The EVR contains a processor that allows for programmable control overthe multiple functional elements contained in the MWT system. The EVRcontains an internal memory device and has dataports that allow forexporting data from the EVR to a portable storage device or by wire orwirelessly to a computer or electronic medical record system. Thisdataport can be bi-directional in certain embodiments, allowing elementsof the electronic medical record (e.g., vital signs) to be incorporatedinto internal algorithms that prescribe MWT or set off alarms. Forexample, acute changes in heart rate and blood pressure along withhigher than normal flow rates of effluent from the wound, can trigger aflow alarm and response, which includes immediate cessation of vacuum.Further, specialized programmed algorithms can prescribe specificsequence of events in the MWT which dictate precisely the timing andduration of irrigation, suction, bladder inflation, ultra-sonicagitation or any combination of the MWT modules described herein thatare utilized in treating a specific wound. The EVR will have the abilityto control when different aspects of the dressing are activated, makingthis a programmable mechanical wound therapy dressing. The EVR will bemanufactured with set algorithms loaded to the system, and it will havethe ability for end-users to enter custom programs or customize existingprograms of therapy, monitoring and alarming. For example, settingcyclic patterns of irrigation and vacuum to increase wound cleansing ininfected wounds. This additional element of the “smart dressing” conceptallows for specific wounds to be treated in different methods, tailoringcare.

An additional embodiment allows for a fluid gas separation system thatis independent of gravity or position of the collection element. Thissystem might include a malleable bag that can contain highly absorbentballs to separate fluid from air but still allow passage of air throughthe bag, for example, as depicted in FIG. 6A. The size of the bag canvary based on the estimated amount of exudates to be collected from thewound. The bag could be similar in size and shape to a standard IV bagmade out of plastic, rubber, latex, or other polymer. It may be ofdifferent sizes or amounts of expected fluid collection to aid in intakeand out take measurements by clinical care providers. Conventionalsystems usually require the collection canister to be upright andtypically hard. One benefit of such a system described herein is that ittends to eliminate the need for a rigid collection canister that usesgravity and a stationary post to hold the canister upright. This systemwould allow for more mobility and transfer well to the out-patientsetting. The bag or system can be worn on a belt with a portable vacuumsource. Filters can be incorporated into the system to preventbiological matter from proceeding past the collection bag and into theEVR or vacuum source. These collection bags are generally disposable. Amoisture sensor or humidity monitor can be incorporated to indicate whenthe bag should be changed. An alternate monitoring system monitors theresistance to flow through the specialized collection bag. As thehydrophilic material becomes saturated it might expand and reduce theflow or increase the resistance to flow which can be monitored and usedto determine saturation of the hydrophilic material. Once a threshold ofmoisture was surpassed, an indicator in this embodiment sounds tosignify that the bag needed to be changed. Additionally, a weight sensormay be used to determine when the collection bag was saturated withfluid. The cut off weight would be determined by the amount of fluidexpected to saturate the collection bag. As fluids—that is, exudateswhich would mostly be water—are collected the weight of the bagincreases. The saturation weight may vary based on the expected volumeof water collected for the size of the collection bag. Something assimple as a moisture sensor patch may be incorporated on the side of thecollection system that turns colors as the moisture meets somepredefined threshold. One example of such moisture cards are AGM(Tucson, Ariz.) moisture cards that change from blue (dry) to pink(wet). Other like types of moisture cards may be used as well. The bagis typically configure with an inflow port and an outflow port on theopposite side. A quick-connect, featured in some embodiments, allows thebag to be easily changed when full.

One embodiment allows the fluid air mixture to flow between balls of afixed similar to air traveling between marbles. In some implementationsof this embodiment variable sized balls are used. The balls can standalone or with cage like coverings that maintain a constant shape. Thehydrophilic balls expose the fluid/air mix to a highly absorbentmaterial across a significant surface area. The cages would givestructure to the absorbent material to prevent complete collapse andblockage of the flow of air. As the mixture of air and fluid passesacross more balls, the gas tends to become more dry. A series of bagscan be used if needed to ensure complete capture of fluid.

An alternate design features a specific column or tubular structure witha series of circular channels to allow air/fluid mixture to pass,filtering out the fluid phase as it passes down the separation column,for example, as depicted in FIG. 6B. In at least some embodiments thewalls of the channels create a cage-like structure for holding superabsorbent material that tends to dry the air as it passes down thetunnel or channel. A one-way anti-microbial/anti-viral filter can beplaced at the egress end of these collapsible versions of the collectiondevice to cleanse/decontaminate the outgoing air. One example of thistype of filter the HEPA (High Efficiency Particle Arrestor/air filter)manufactured for biological use. The filter of this embodiment may bepositioned in various locations in the MWT system, but is typicallylocated at or near the air output exit duct of the EVR, that is, thepoint where the air from suction gets expelled to the outsideenvironment.

Air and water are fluids, and as such, they tend to follow the path ofleast resistance. The present inventors recognized a flaw ofconventional system involving the fluid path of the irrigant. When apath for irrigation instilled onto the dorsal surface (the side of thewound filler that is opposite the wound bed) of a conventional NPWTdressing is allowed unrestricted communication to an outflow system thatis kept under negative pressure, the fluid will pass from high to lowpressure and circulate on the side of the dressing opposite the wound,rather than following a path of greater resistance through wound fillingmaterial to the actual wound surface. This flaw of conventional systemsis overcome by several elements of the various embodiments disclosedherein. For example, some embodiments feature a spatial orientation ofthe dressing in which the irrigation component is placed in closestproximity to the wound, separated from the vacuum source, such that theflow path of irrigant tends to be directly across the wound surfacerather than through or over the top of the wound filler. The manner ofoperation of these embodiments is superior to the conventional systemsthat attempt to circumvent the design flaw by ceasing vacuum suctionduring the application time of the in-flow irrigating fluid. In systemsthat have a wound filler, this simply means saturating the filler untilthe fluid leaks to the wound surface. In systems both with or without afiller this can lead to pooling of fluid under the dressing seal. Thepresent inventors recognized the advantage of implementing irrigation asan active process featuring both the application and simultaneousremoval of the irrigant. In this way, the irrigation system of thevarious embodiments tends to be maximally effective. This innovationallows for the irrigation component in this MWT device to act in alavage mode, which serves to better wash/cleanse the open wound, whichis an important element of open wound care that currently is not offeredby conventional systems. Due to this weakness in the current art,repetitive surgical operations or procedures are instead required toattain a similar effect.

Additionally, an alternate embodiment would allow for controlleddelivery of alternating irrigants, for example, as depicted in FIG. 3B.This embodiment can alternate between a fluid irrigant and a gaseousirrigant or between different types of fluid irrigants, like anantiseptic agent, immediately followed by normal saline or water, tonegate/reduce the cytotoxic effects of some potent antiseptics. Byalternating the irrigants, the lavage would allow for increasedagitation and mechanical debridement as well. A fine filter can be usedto prevent contamination of the wound when using nonsterilized gas(e.g., air). A back flow valve may also be utilized to preventretrograde flow of the irrigant from the sealed dressing, back into theirrigation conduit tubing.

Pooled fluids tend to weaken the seal of the wound dressing, oftenleading to increased dressing failures. Pooled fluid will leak towardthe occlusive dressing and its seal with the intact skin margin. Thisadhesive interface has and will continue to be a weak point in NPWTdressing function. Most adhesives tend to lose their adhesive quality asthey become wet. In conventional systems the seal between the occlusiveportion of the dressing and the skin is the most common site ofcorrectable failure for NPWT dressing (e.g., “leak”). A conventionalirrigation system, which requires the vacuum to be stopped during thein-flow period, because the system's construction requires sharingtubing or passageway/flow-paths between in-flow (e.g., irrigation) andout-flow (e.g., vacuum), puts additional stress on the adhesive seal.Thus, conventional NPWT systems, while they may solely function in theapplication of a vacuum to a wound surface, with certain and clinicallyreal limitations, cannot function as the outflow side of an integratedMWT device. Various embodiments disclose a means for providing regulatednegative pressure to a wound, which can be regulated to applysimultaneous continuous or intermittent vacuum during periods ofirrigation. The EVR can regulate irrigation and vacuum elements. The EVRcan control the pattern of intervals of simultaneous or sequentialfunctioning of these two elements. Algorithms for irrigation and vacuumapplication can be programmed on the EVR at fabrication, with theability of the end-user to customize algorithms and store the customalgorithm as well on the EVR. Additionally, a means of accounting forspecific volumes of irrigation passed through the MWT system can beincorporated. For example, the EVR is programmable to increase thethreshold for flow alarms during periods of irrigation to prevent falsealarms for elevated flow rates. As previously described, this abilitywill prevent false alarms by preventing alarms from sounding forincreased volume collection being interpreted as increased blood loss.For example a 1 liter button can be pushed to allow the EVR to expect aliter of irrigation to be collected over the next predetermined timeframe preventing an alarm from sounding when the system detects increaseflow by suction. Further, this will allow the EVR determination ofoutput/wound drainage to be automatically corrected for the irrigationfluid volume. In other embodiments, the system can record the flow rateand volume of irrigant infused in real-time, which is then reported tothe EVR, to again allow the EVR to exclude externally applied volumes offluid in its computation of flow rate, as it pertains to the flow alarmand response to vacuum-assisted exsanguination response algorithm.

One aspect of the various MWT embodiments is the ability to implementintegrated, simultaneous vacuum and irrigation. This allows periodiclavage of the wound surface, which in turn, helps to mitigate bacterialload/biofilm and reduce exudate/fibrin build-up. Layered, unidirectionalwound filler filled and/or single layered versions of the MWT dressingmay include tubes which convey fluids away from the wound underregulated vacuum control, and a second set of separate closed tubingsystem that conveys fluid irrigant to the wound. The irrigant can bevaried to adapt to the situation and the course of treatment. Forexample, the fluid irrigant may be potable water, saline, antibiotic,antiseptic or filtered gas (e.g., oxygen) or alternated betweendifferent irrigant options.

In some embodiments, the fluid in-flow and out-flow tubing meet at thewound surface. In other embodiments, the in-flow tubing is maximallydistanced from the out-flow egress. For most embodiments, the path fromin-flow to out-flow occurs across the wound surface, which is thelocation where this fluidic communication should occur, for situationsin which the goal is to provide wound irrigation. The design of thevarious embodiments ensure irrigation and effluent flow pathscommunicate to all parts of the wound. This allows for continuous andintermittent irrigation modes, which can be pre-programmed or left forcustomization by the end-user. In various embodiments the two separatetubing systems do not come to a central common point, but rather,maintain separate ingress and egress for each system, such that the onlycommon location between the two is the wound surface. In variousembodiments, the tubing systems typically communicate through a chamberor flange to a dual-lumen tubing system (one suction, one irrigation).In such embodiments the tubing communicates on one side retrograde tothe collection canister and then the vacuum source and on the other sideantegrade from a irrigant source. In this way the fluid can becontrolled to flow passively or actively into the wound where it isevacuated by simultaneously or sequentially applied vacuum through theegress tubing system.

An exemplary embodiment of this dressing has a central vacuum woundinterface chamber, for example, as depicted in FIG. 1R, or flange(s),for example, as depicted in FIG. 1S adjacent to a central tubingconnection point with or without accessory vacuum tubing distal to thispoint. A completely separate tubing system bypasses this vacuuminterface to extend to the deepest layer (e.g., layer closest to thewound surface) where it fludically connects to the radial or spider-weboriented irrigation tubing system, that centripetally extend from acentral point to the periphery, allowing for maximal customizability,which would not be possible in a dressing that has independentperipheral members. Tubes of set inner diameters, that typically arechosen to equal the diameter of fluid passage holes in the tubes thatface in three directions (both horizontal planes (e.g., left and right)and then deep (e.g., towards the wound surface) to deliver irrigant tothe wound surface. In this exemplary embodiment, the two tubing systemsremain separated by being situated between different layers of thelayered dressing and have completely dedicated tubing/conduit systemsfrom source to wound bed, allowing for activation of either systemsimultaneously or at set intervals to each other, to most effectivelyirrigate and remove the irrigant from the wound surface. The deepest(wound facing) layer can be abrasive to provide amicro-abrasion/debridement effect when the dressing is agitated by thepositive pressure bladder described herein or simply through contractionof the underlying muscle.

Additionally, the dressing affords some structural integrity to allowthe dressing to be secured to the skin edge prior to obtaining a dorsalseal with either staples or sutures. By securing the position of thedressing, this process allows for small motion for micro-debridementeffect, but not too much to allow seal disruption. This process can onlybe performed if the dressing has some structural integrity to allow itto be fixed to the wound edge. Further this quality of the MWT dressingplatform can resist the normal tendancy for skin margins of large openwounds to initially spread, especially in the setting of traumaticswelling. The structural integrity is provided by the netting, mesh orthin perforated film layered construction.

At least some embodiments feature a pulse lavage function where theirrigation tubing line is charged (e.g., loaded from source to woundwith irrigant) and then active pulse pressure is applied, withsimultaneous negative pressure from the vacuum side. This allows pulsedpressure lavage irrigation, which is not described nor enabled by thecurrent art. Forcing fluid directly across the wound surface underpressure (typically low pressure), more effectively cleanses the wound,as it works to cleanse the wound through a mechanical effect and throughthe solubilizing effect of having a fluid in contact with the woundsurface. Current art at most allows for the solubilizing effect thoughirrigant instillation, but does not allow for the mechanical effect,which is as effective or more effective at cleansing the wound surface.This same mechanical cleansing effect can be produced by the reversepulse lavage mode of irrigation described herein. In other embodiments,passive irrigation is created by simple gravity in-flow. Typically, thevacuum source is separated from the dressing/irrigation tube system by avalve or other control feature that regulates the degree to which theirrigation system is affected by the vacuum system. In at least someembodiments, this control mechanism is a one-way valve that allowsirrigation to flow to the wound surface in the setting of appliednegative pressure within the dressing. Distal to this valve is a crimpor similar that closes the irrigation tube, so that the one-way valve inthe irrigation tubing only sees vacuum when irrigation therapy isdesired. In some embodiments the vacuum side of tubing has a tubing portconnection that allows for fluid to be injected to aid in clearing aclog or blockage in the system, followed by immediate resumption of thevacuum. Further, this vacuum side tubing port can be used to sample theeffluent. The irrigation side tubing may be configured with additionalports as well for injection of adjuvant agents.

An additional embodiment allows for an alternating valve to allowgas/air and fluid to be alternated, for example, as depicted in FIG. 3B.This valve can alternate between allowing fluid such as IV fluids andgas such as air to be pulled by the suction on the reverse pulse-lavagesetting in a set fashion. The air may travel through a filter to preventmicrobial contamination. This alternating system would allow theirrigant to be cleared before pulling more fluid across the wound. Thissystem would prevent pooling while still performing its irrigationfunction.

Edema fluid tends to collect at sites of soft tissue inflammation. Thiscomplicates wound healing by multiple mechanisms, like increasing thevolume of the wound, retracting skin margins and reducing capillaryperfusion. Various embodiments disclosed herein help to mitigate thisproblem by using an inflatable bladder that applies pressure to thewound. Pressure is applied on the wound using the inflatable bladderthat preferentially expands towards the wound surface. This preferentialexpansion and therefore pressure application is caused to occur byvarious means, like placing a sleeve over the affected extremity,placing the bladder between the wound approximating device and thesealed MWT dressing, affixing the bladder to the skin margins or throughconstruction, with more pliable ventral material compared to dorsal. Thepressure would vary based on clinical desires and use. The range couldbe controllable based on desired effects (e.g., venous congestion, DVTprevention, edema control, skin closure, wound debridement). Specificpressure values can be set for different uses. A range from 0 to 30 mmHgmay be used in a typical situation, although pressures exceeding 30 mmHgmay have clinical utility in specific conditions. The bladder can beinflated with gas or liquid, which can be pre-heated or pre-cooled,under control of a temperature control unit, to provide an additionalmode of therapy. The temperature control unit may be embodied as avariable switch connected to heating/cooling units in contact with theliquid or gas used to fill the pressure bladder. Cooling could be downto or below 32 degrees Fahrenheit such as using ice water or a solute inwater solution that can be cooled external to the bladder. Applying iceto an injured extremity tends to reduce and/or inhibits edema in theacute setting. Heat could be used up to or above 180 degrees Fahrenheitto promote increased blood flow and provide an analgesic effect.Applying intermittent positive pressure to the wound can help “squeeze”the edema fluid which collects at sites of soft tissue inflammation. Thenet effect of this squeezing used in tandem with the wound approximatingsystem described herein is that wound volume can be reduced and thelikelihood of successful delayed primary closure increases. Delayedprimary closure is a preferred mode of definitive treatment to woundstreated by NPWT or MWT. It is generally a cheaper, more cosmeticallypleasing mode (as opposed to skin grafting), which restores fullthickness skin coverage to the wounded site. Pushing on the wound with abladder, then releasing the bladder and applying a wound approximatingforce to the wound margins in a sequential fashion over a sufficientperiod of time will allow closure of the wound in many instances.Pushing on the wound dressing, also serves to reinforce the adhesivelayer's seal and the micro-debridement of the wound surface caused bythe abrasive ventral layer. Additionally, the positive pressure can pumpirrigation fluid in deeper areas of the wound.

The inflation can stretch tissues to prime the tissues for the woundapproximation effect of the integrated MWT system. This componentrepresents a dynamic way of getting edema out and preloading the woundapproximating module. As the bladder inflates, tension in theapproximating system is increased stretching the skin margins to nogreater than a preset force limit, then as the bladder deflates, thewound approximating module, pulls in the stretched skin margins, helpingto sequentially approximate the wound. This preload, reel-in effect isakin to the actions of catching a large fish on a fishing pole. Whenfishing, a forced is applied by pulling back against the fish with therod, the force is released by leaning back towards the fish and reelingin the slack. In a similar fashion, the skin edges are placed intraction by the bladder, once the bladder is deflated, the approximatorreduces the slack thereby assisting in the approximation of the wound.

The bladder also acts like a sequential compression device (SCD) to helpwith venous return and reduce venous congestion/stasis. To this end, thebladder can have multiple chambers, that are inflated/deflatedsequentially. The pressure and rate of inflation is controlled by theEVR under preset algorithms or those custom entered by the end user.However, there are specific clinical situations where the bladder maynot be recommended or applied. The EVR can be pre-programmed or end-userprogrammed, to maximally shift from one therapeutic to the next, toinclude the inflation/deflation cycles of the bladder relative toepisodes of therapeutic irrigation, again supporting the “smartdressing” concept.

Debridement is one of the features in wound care addressed in variousembodiments of the MWT system. The inflatable bladder is one of thecomponents of the MWT system that accomplishes this task. Theinflate/deflate cycling of the bladder will provide some motion of theabrasive wound-facing surface of the dressing, which can stimulatemicro-abrasion or “micro-debridement,” which loosens/clears fibrinslough, exudate build-up and biofilm. The motion provided by the bladderfor the dressing on the wound will include up down (compression) as wellas side to side motion. This motion will also limit tissue in growthwhich allows the dressing to be maintained for longer periods of time.

The bladder can also be inflated and held inflated in a continuousfashion for certain situations, specifically over skin grafts, whereconventionally bolsters or NPWT have been used to ensure the graftremains well approximated to the recipient bed. In this application andsome others, the bladder will be held in place by a sleeve (e.g.,circumferential or with an opening and fastener) that can be placedaround the affected site akin to a SCD stocking, for example, asdepicted in FIG. 7A. In other embodiments, the bladder can have a skirtthat can accept staples or other means for removably affixing thebladder directly to the skin margins. Alternatively, in wounds treatedwith the wound approximating device module, the bladder can be held inplace by the support ribbons/tapes of the overlying wound approximatingdevice. This device can act as a wound approximating device as well as abackboard to direct the force of the bladder towards the wound. If thereis no sleeve, backboard or other means of directing the force applied bythe inflated bladder (e.g. fixing the bladder to the skin margins), thebladder will inflate and expand away from the wound and not direct forcetowards the wound. The torque limiter of the wound approximating deviceprevents unsafe pressures from being applied to the skin at the marginsof the wound while directing a safe amount of downward force towards thewound. The positive pressure bladder can have a secondary effect ofexpediting the approximation of the skin edges to allow for more rapidand/or complete primary closure. Additionally, cold fluid such as icewater can be used to inflate the bladder which would create additionalmeans of reducing edema. This can be alternated to warm fluid in asub-acute setting to promote blood flow and healing. In this way, thepositive pressure bladder is yet another functional element of thissystem that supports the novel concept of mechanical wound therapy.

In most embodiments, the bladder will be unidirectional throughconstruction, having a more pliable surface facing the wound and a morerigid surface facing away, for example, as depicted in FIG. 7B. The morepliable surface will direct positive pressure towards the wound,directing the pressure into the undulating, uneven surfaces and/orshallow crevices of the wound.

For an additional therapeutic effect, the bladder, in some embodiments,can be inflated with warmed or cooled fluid to provide warmth or coolingto the wound bed and underlying injured tissue. This temperature therapycan further reduce edema, swelling and/or pain. This can be alternatedto warm fluid or between warm and cool fluid in a sub-acute setting topromote blood flow and healing. Inflation of the bladder with thetemperature controlled fluids can be held for periods or time orfrequently cycled as specified by the end-user through a controlfunction integrated in the electronic vacuum regulator.

Additionally, a more pliable undersurface would allow the uneven woundto be fully treated. As the bladder expands, it will fill the deeperundulations and allow an even force to be applied to the whole wound. Aless pliable bladder would create pressure points where some areasreceive the force while others do not.

An additional embodiment for the positive pressure bladder mayincorporate a ultrasound device or electromagnetic device within eitherthe bladder or dressing itself. The use of these type devices would betwo fold. If the injury included a bony injury, these two modalitieshave been shown to have beneficial effects on bone healing.Additionally, ultrasound placed within a fluid filled bladder canproduce vibrational agitation that can improve wound cleansing.

Skin and fascia both have an elastic property that passively retractswound edges left open over time. This process can be increased byswelling of the muscle and subcutaneous tissue. Left to its own, theonly competing force to the centripetally outward egress of skin marginsin open wounds is the cellular fibroblastic response in granulationtissue, which over a long period of time produces some uncontrolledcontraction of the wound. Generally, this does not result in primaryapposition of skin surfaces, but rather dense central fibrosis thateventually epithelializes. Various embodiments of the MWT wound caresystem account for this process. The various embodiments are capable ofsecurely coupling the skin margins to the dressing. Some conventionalsystems rely on non-integrated tensioning devices that are separate andact independent of the NPWT dressing. Likewise, some conventionaltensioning devices exist which are not integral to the NPWT device. Inboth situations, the lack of integration, compromises the individualfunctions, for instance, some conventional tensioning devices need to beapplied beneath the sealing adhesive layer of the NPWT, which increasesthe risk of leak.

Various embodiments disclosed herein feature an integrated woundapproximating device designed to provide dermatotraction (approximationof the skin margins) without compromising the function of the underlyingNPWT dressing. This aids in halting and reversing expansion of the wounddimensions. Further, the integrated wound approximating device of thevarious embodiments allows a controlled and directed amount ofapproximating force to be applied to the skin margins to sequentiallyclose down the wound.

Another embodiment of the integrated wound approximating device featuresan integrated modular component that is placed over the sealed basic MWTdressing. In various embodiments it is considered modular since, inthose embodiments, it may be implemented as an independent device. It issecured to the skin margins with staples, sutures or other means oftemporary fixation over a previously applied and sealed MWT dressing. Inthe most typical form, the modular component has a central crankshaftaround which are wound ribbons or tapes that are affixed centrally tothe crankshaft and distally to two pull-tabs. Centrally there can be aring that slides over the central tubing connection point of the basicMWT dressing. This acts to anchor, but not necessarily through rigidconnection, the wound approximating device module to the basic MWTdressing of this integrated system and to keep the crank-shaft orientedin the long axis of the wound. The pull-tabs are then pulled away fromeach other, from the rolled position, out to a length sufficient forthem to overlie normal skin. This action is akin to unrolling a shade ona window to a desired length. The pull-tabs have an adhesive back thatprovide temporary fixation to the skin or adhesive film of the basic MWTdressing. Then staples, sutures or other means of fixation can be placedthrough the pull-tab or ribbons/tape to firmly affix the approximatingdevice to the skin. In a common embodiment, a rubberized central corewill exist in the pull tab, that has enough integrity to not allow thestaple to pull through, but soft enough to be stapled through to affixthe pull tab to the skin. This rubberized material will provided a selfsealing effect about the staples, as well. A sufficient number ofribbons/tapes per unit length are used to reduce number of staplesneeded, but also spread the stress on the skin over a sufficient numberof fixation points (e.g., 1 rib/tape every 2 cm). If desired, a skinglue, stoma paste, or similar product can be placed over the staples toensure that their perforation through the pull tab and the underlyingadhesive sheet of the basic MWT dressing, does not disrupt the seal, forexample, as depicted in FIG. 6A.

Turning again to FIG. 9B, a removable crank 980 may be attached to theend of the central crankshaft so that it can be turned manually. Thecrank 980 may be embodied as a ratchet type mechanism. The centralcrankshaft—for example, the crankshaft 970 of FIGS. 9A-9B—may beconfigured with a torque limiting feature that prevents generating apulling force above a threshold that is potentially harmful to thepatient. The crankshaft is the central origin for the ribbons in thewound approximating device, around which the ribbons are wound as thecrankshaft rotates. The manual crank 980 can be attached directly to theterminal pole of the crankshaft 970 or through an appendage, thatextends some distance (e.g. 2 to 10 cm) between the cranking element andthe central crankshaft to allow access to the crank without having toremove the dressing or splints that may be present on the injured site.Different amounts of approximating force would be useful in differentsituations. Therefore, multiple torque limiters can be used in seriesthat will allow for different maximal tensions to be created atdifferent times during therapy. In some embodiments, a series of torquelimiting springs or devices are incorporated, each with its own maximalapproximating force threshold. Alternatively, a single torque limiterthat is adjustable over a range may be used. The provider or end-usercan select the maximal force setting (e.g. high or low) that is mostappropriate for the wound. Typically, this will require moving a switchthat engages the selected spring or torque limiting device. Thisspecific embodiment of the torque limiting feature of the woundapproximating device may be particularly well suited for some wounds forwhich maximal approximating force should be kept low initially (e.g.fasciotomy wounds), however with time and tissue relaxation, the safethreshold for approximating force can increase. In addition, there is astop catch, that can be released, that holds each increment of forceadded through rotation of the crank, but can be released, to release theforce if desired. Alternatively, the crank can be spring operated toapply a specific amount of continuous force to the skin margins. A pinor other like type of mechanism can be activated that temporarily orpermanently halts and/or reverses the continuous force application, asdesired. Lastly, in the setting of an open abdominal wound, a specificembodiment of the wound approximating device is connected to the fascia(rather than the skin), to approximate the fascia, thus allowing forprimary closure of the fascia or to minimize the area of fascialgraft/defect that is left, when the overlying cutaneous layer is finallyclosed/covered.

In some embodiments, a central spring with torque limitation that isactivated when a set magnitude of force or duration of force isexceeded, can provide time-sensitive, graded force control. For example,the torque limiter, which releases or reduces force, can be activatedwhen an unsafe injurious magnitude of force is obtained at any instance,or when a sub-injurious, but non-beneficial force is maintained for anunacceptable period of time. We therefore describe force limiters thatrespond to a threshold absolute magnitude of force or a specificduration of a sub-maximal threshold force that is maintained for a setperiod of time, both of which result in automatic relaxation of force.An exemplary embodiment would include, the maximum force the device canapply is set as a high force value. Any load over the higher limit wouldautomatically be released back down to the preset value. In addition,the torque limiter can be set to respond in the event a force less thanthe higher limit is applied for a predefined period of time, resultingin a release of force to a lower force that is a safer value that can betolerated for sustained periods of time. This feature would allow forthe bladder to apply a higher but transient force up to a higher limitfor short periods of time (seconds to minutes). If force exceeds thelimit for more than a predetermined time frame the force limiteractivates to release unsafe sustained higher force that could causeisehemia or injury to the tissue. The ability to tolerate transienthigher, but still non-injurious, force applications would allow for moreforce to be placed on the skin edges at certain times to close the woundor stretch the skin for primary closure. As the skin has the elasticpotential to expand a wound, so too does it have the ability to stretchto enable it to cover the wound. Pregnancy demonstrates the amazingpotential of the skin and subcutaneous tissue to stretch in response tosustained pressure.

Some embodiments of the integrated wound approximating device module ofthe MWT system employ nonabsorbable sutures with needles on theperipheral end of the dressing or with loops at the peripheral ends thatcan be stapled to the skin edges to firmly grasp the skin margins of thewound. These supports would converge on a central portion of the wound.In this fashion the wound approximating device can be incorporated intothe basic dressing proper, but typically is a separate module, that isapplied as needed over the basic dressing.

Other embodiments employ tabs at the end of ribbons of material thatroll around a central shaft. These tabs can have adhesive on one surfaceto assist in fixation of the tabs to the wound margins. In addition,staples can be applied through the tabs or rib material to further affixthe wound approximator to the wound margins. The tabs can have a centralgel or softened plastic material that seals the staples to the tabs asthey penetrate this material, the sealing adhesive sheet and theunderlying skin margin, to prevent or greatly limit the risk of leak atthis fixation site. The adhesive underlying the tabs, further aidsagainst the creation of leaks in the system, when the woundapproximating module is added to the MWT dressing. The attachment of theribbons/ribs and the pull tab can be permanent such as glue or othermeans or it can allow for detachment and reattachment such as Velcro®,snaps, ties . . . . The removable fixation methods at the ribbon tabinterface, specifically Velcro® or snaps, or hook and loop or othermeans can afford another layer of safety against exceeding safethresholds of approximation force, as the Velcro® or snaps are selectedfor their release properties at specific forces, such that they releaseat undesired levels of pulling force in a breakaway fashion. By enablingfor selective or total detachment or breakaway, the central spine can beremoved to allow inspection under the wound approximating device withoutremoving the staples attaching the tab to the skin, as depicted in FIG.9A. This breakaway feature is both protective as well as practical whichis unique to the current design that is not present in the current art.The ability to remove and replace the approximating device withoutremoving any of the invasive aspects (staples) will allow inspection ofthe wound as well as the seal without needing to reapply the fixationwhich is typically painful (staples). Also as the corners are pulledtogether in an elliptical wound, the outer ribs can be released to allowfor continued force in the central or wider aspects of the wound, forexample, as depicted in FIG. 9B. This design is also unique to thecurrent design. This allows for selective approximation in certain areasof the wound. Conventional art requires all aspects to be tensionedsimilarly and does not allow for modifications as wounds close. One areaof the wound cannot be selectively tensioned without removing andreapplying the entire device. For these reasons, the ability to releasethe ribs from the pull-tabs, represents a novel, useful improvement overcurrent art that speaks to the approximation of wounds. This feature isintegral to adding versatility to the approximating device.

An approximating dial or shaft featured in certain embodiments isconfigured to contain a standard approximating force. At a prescribedrate and/or magnitude force can be applied to these supports which wouldcentripetally in circular wounds and transversely in elliptical wounds(like a fasciotomy wound), act to pull the skin margins in towards thecenter point or long axis of the wound. In some embodiments as themargins are brought centrally, the tubular portions of the basic MWTdressing in a specific pattern will fold on themselves in apredetermined fashion (similar to a folding bed or collapsible chair).The limited volume on the wound surface occupied by the collapsingdressing acts akin to a tissue expander as the supports are sequentiallyclosed over, creating a small dead space in the wound and laxity in theapproximated wound margins, to support a tensionless or limited tensiondelayed primary closure. At the same time, the mesh, netting or thinperforated film construction of each layer, provides ample dead space inthe dressing to allow the dressing to collapse to a large degree uponitself, so as to not impeded the wound approximation effect of theintergraded MWT system. Thereby, creating the greatest chance atensionless delayed primary closure may be undertaken for definitivesoft tissue management at the cessation of MWT. In wounds with tenuousedges (e.g., post-radiation areas) or with large segmental skin defects,the controlled and metered force can at a minimum reduce in size thearea required for skin grafting or to be left to heal by secondaryintent when the MWT is discontinued. In certain embodiments, themagnitude and/or rate of force can be set or adjusted by the end-user,for instance reduced in the setting of tenuous skin margins or pediatricor elderly patients. Ranges of tension could be adjusted using anadjustable torque limiter that would allow for different amounts ofapproximating force to be applied based on the clinical situation.

Additional embodiments may utilize a flexible center shaft to allow forbetter fit along the wound surface. Additional embodiments may allow formultiple smaller wound closure devices versus a single device. Also, thesize of the wound closure device may be varied or expanded or shortened.Also multiple sizes can be produced to allow the end-user to choose anappropriate size. An additional embodiment would allow for the device tobe made only from ribbons or cords to allow appropriate management ofmore non standard wound shapes.

As described above, this device is also an integral part of the wholesystem, which will provide a backboard for the positive pressure bladderwhen used in conjunction with the MWT system, as depicted in FIG. 8A.This device allows for safe and directed force from the bladder towardsthe wound. By using the two combined in a unique and novel system, theability of each to perform its function is maximized. The bladderprovides increased cyclical dermatotraction on the skin edges to promotefurther approximation of the wound through tissue expansion while alsodecreasing swelling, one of the primary reason the wound will not close.The positive pressure bladder in conjunction with the dynamic backboardeffect of the wound approximating module, allows for a directed force tobe applied to the wound, that can provide compression and temperatureregulation as well as micro-motion of the abrasive dressing to promotewound debridement. Additionally, the force can reinforce the seal alongthe wound edge by compressing the dorsal layer.

The various embodiments of MWT features for controlling and/or reducingthe microbial load on the wound through the application of adjuvanttherapy modules. For example, certain embodiments are configured toprovide microbicidal doses of ultraviolet light, typically UVCradiation, to the wound surface in metered doses to eradicate or reducein number microbes on the wound. UVC rays have therapeutic effects thatare currently used to treat superficial infection (e.g. ophthalmic) andhave a proven safety record in medical applications. An example is theBiomation Thera-Wand C100 for wound care. The range for light wave forUV light is 100-400 nm. UVC light which has shown the best antimicrobialeffects are from 100-280 nm. The UVC light would be produced by aseparate generator. At least some embodiments employ fiberoptic elementsor other means for transmitting UVC light from the dorsal surface of thedressing to the surface of the wound. Some embodiments are configured todeliver gases, for example; oxygen or ethylene oxide, through theirrigation system across the wound surface again to eradicate and/orreduce in number microbes on the wound. Supplemental oxygenspecifically, has demonstrated clinical efficacy in reducing woundcomplications and infections. Conventional clinical applications requiresystemic delivery through inhalation of air with high partial pressuresof oxygen or expensive hyperbaric oxygen chambers. Direct delivery ofhigh concentrations of oxygen to the wound surface via the irrigationtubing system described herein, ensures that the highest partialpressures of oxygen dissolved into body fluids are achieved at the woundsurface where they provide the most benefit, avoiding the issues relatedwith systemically administered supplemental oxygenation.

In addition, ultrasonic vibration can be applied to the wound, orthrough, the dressing to assist in debridement and loosening thebiological films that form at the wound surface. This micro-debridementtechnique can mechanically cleanse the uneven wound surface in a gentle,non-thermal fashion with limited or no zone of injury. This adjuvantmodule, augments the micro-abrasion/micro-debridement effect of theabrasive ventral surface of the basic dressing and the mechanicalpush/pull effect of the modular positive pressure bladder system.Ultrasonic transducers can be incorporated into certain embodiments ofthe basic MWT dressing, including the layered, single layer andunidirectional embodiments, that can be contacted/connected toultrasonic source to apply the vibration to the dressing and/or woundsurface. In some embodiments, the entire ultrasonic vibration generatorand transducer can be a single unit with its own power supply integratedinto the dressing. This can have an on/off switch or can be wired orwirelessly connected to the EVR to be programmably controlled. Theultrasonic transducers can be incorporated, so that they sit in fluidiccommunication with the wound surface. Alternatively the ultrasonicagitation can be delivered from a distance external (non-contact).Additionally, an ultrasonic adjuvant module may be incorporated into thepositive pressure bladder module where a fluid used to inflate thebladder transmits the ultrasonic vibration through to the wound surface.The effectiveness of the ultrasonic agitation can be augmented withsimultaneous irrigation of the wound with specific solutions (e.g.,ionic solutions) to improve transmission of the ultrasonic waves.

Adjuvant medical device applications are integrated in a modular design.In addition to wound healing adjuvants, bone-healing adjuvants likeultra-sound and/or pulsed electromagnetic fields can be added as amodular layer, external to the sealed basic MWT dressing. One suchexample of this technology would be the Exogen (Smith and Nephew®) bonehealing system. These can be placed directly over the fracture andfacilitate healing in the setting of infection or massive soft tissueloss or other challenging wound healing environments, where definitiveclosure/coverage may not be possible for a prolonged time.

FIG. 17 depicts a computer system 1700 and components suitable forimplementing the various embodiments disclosed herein. The computersystem 1700 may be configured in the form of programmed microprocessor,a laptop computer, a desktop computer, a mainframe computer, or anyother hardware or logic arrangement capable of being programmed orconfigured to carry out instructions. Depending upon the particularitiesof the embodiment, the computer system 1700 may not include all of thecomponents depicted in FIG. 17 (e.g., computer 1700 may not include akeyboard or mouse 1713, disk drives 1707, and/or other componentsdepicted in the figure). In some embodiments the computer system 1700may act as a server, accepting inputs from a remote user—e.g., acceptinginputs from laptop 1733 or desktop computer 1729—over a wireless node1735, the Internet 1723, or other communication channel. The computersystem 1700 may be located and interconnected in one location, or may bedistributed in various locations and interconnected via communicationlinks such as a wireless node 1735, a wide area network (WAN), via theInternet 1723, an intranet 1731, via the public switched telephonenetwork (PSTN), a switching network, a cellular telephone network 1725,a wireless link, or other such communication links. Other devices 1727may also be suitable for implementing or practicing the embodiments, ora portion of the embodiments. Such devices 1727 may be embodied as apersonal digital assistant (PDA), a wireless handset (e.g., a cellulartelephone or pager), or other such electronic device preferably capableof accepting inputs for instructions or commands. Those of ordinaryskill in the art may recognize that many different architectures may besuitable for the computer system 1700, although only one typicalarchitecture is depicted in FIG. 17.

Computer system 1700 may include a processor 1701 which may be embodiedas a microprocessor, two or more parallel processors, a centralprocessing unit (CPU) or other such control logic or circuitry. Theprocessor 1701 may be configured to access a local internal memory 1703,e.g., local cache memory. Some embodiments may integrate the processor1701, and the internal memory 1703 onto a single integrated circuit andother embodiments may utilize a single level cache memory or no cachememory at all. Other embodiments may integrate multiple processors 1701onto a single die and/or into a single package.

The internal memory 1703 may include one or more of random access memory(RAM) devices such as synchronous dynamic random access memories(SDRAM), double data rate (DDR) memories, or other volatile randomaccess memories. The internal memory 1703 may also include non-volatilememories such as electrically erasable/programmable read-only memory(EEPROM), NAND flash memory, NOR flash memory, programmable read-onlymemory (PROM), read-only memory (ROM), battery backed-up RAM, or othernon-volatile memories. In some embodiments, the computer system 1700 mayalso include 3^(rd) level cache memory or a combination of these orother like types of circuitry configured to store information in aretrievable format. In some implementations the internal memory 1703 maybe configured as part of the processor 1701, or alternatively, may beconfigured separate from it but within the same package. The processor1701 may be able to access internal memory 1703 via a different bus orcontrol lines than is used to access the other components of computersystem 1700.

The computer system 1700 may also include, or have access to, one ormore storage drives 1707 (e.g., hard drives, optical disk drives, orother types of storage memory). The internal memory 1703 and storagedrive 1707 are examples of machine readable (also called computerreadable) mediums suitable for storing the final or interim results ofthe various embodiments. The disk drive 1709 may be embodied as anoptical disk drive configured to operate with one or more of variousformats that can read and/or write to removable storage media (e.g.,CD-R, CD-RW, DVD, DVD-R, DVD-W, DVD-RW, HD-DVD, Blu-Ray, and the like).Other forms or computer readable media that may be included in someembodiments of computer system 1700 include, but are not limited to,floppy disk drives, 9-track tape drives, tape cartridge drives,solid-state drives, cassette tape recorders, paper tape readers, bubblememory devices, magnetic strip readers, punch card readers or any othertype or computer useable or machine readable storage medium.

The computer system 1700 may either include the storage drive 1707 andoptical disk drives 1709 as an integral part of the computer system 1700(e.g., within the same cabinet or enclosure and/or using the same powersupply), as connected peripherals, or may access the storage drives 1707and disk drives 1709 over a network, communication channel, or acombination of these. The storage drive 1707 may include a rotatingmagnetic medium configured for the storage and retrieval of data,computer programs or other information. In some embodiments, the storagedrive 1707 may be a solid state drive using semiconductor memories. Inother embodiments, some other type of computer useable medium may beused. The storage drive 1707 need not necessarily be contained withinthe computer system 1700. For example, in some embodiments the storagedrive 1707 may be server storage space within a network that isaccessible to the computer system 1700 for the storage and retrieval ofdata, computer programs or other information. In some instances thecomputer system 1700 may use storage space at a server storage farm, orlike type of storage facility, that is accessible by the Internet 1723or other communications lines. The storage drive 1707 is often used tostore the software, instructions and programs executed by the computersystem 1700, including for example, all or parts of the computerapplication program for carrying out activities of the variousembodiments.

The communication link 1705 may be used to access the contents of thestorage drive 1707 and disk drive 1709. The communication links 1705 maybe point-to-point links such as Serial Advanced Technology Attachment(SATA) or a bus type connection such as Parallel Advanced TechnologyAttachment (PATA) or Small Computer System Interface (SCSI), a daisychained topology such as IEEE-1394, a link supporting various topologiessuch as Fibre Channel, or any other computer communication protocol,standard or proprietary, that may be used for communication to computerreadable medium. The memory/bus controller may also provide other I/Ocommunication links 1705. In some embodiments, the links 1705 may be ashared bus architecture such as peripheral component interface (PCI),microchannel, industry standard architecture (ISA) bus, extendedindustry standard architecture (EISA) bus, VERSAmoduleEurocard (VME)bus, or any other shared computer bus. In other embodiments, the links1705 may be a point-to-point link such as PCI-Express, HyperTransport,or any other point-to-point 110 link. Various I/O devices may beconfigured as a part of the computer system 1700.

In many embodiments, a communication interface 1711 may be included toallow the computer system 1700 to connect to the Internet 1723 or othernetwork such as that of wireless node 1735. Such networks may operate inaccordance with standards for an IEEE 802.3 Ethernet network, an IEEE802.11 Wi-Fi wireless network, or any other type of computer networkincluding, but not limited to, LANs, WAN, personal area networks (PAN),wired networks, radio frequency networks, powerline networks, andoptical networks. A network gateway or router may serve as, or be acomponent of, an intranet 1731, which may be a separate component fromthe computer system 1700 or may be included as an integral part of thecomputer system 1700, may be connected to the wireless node 1735 and/orInternet 1723 to allow the computer system 1700 to communicate with theInternet 1723 over an internet connection such as an asymmetric digitalsubscriber line (ADSL), data over cable service interface specification(DOCSIS) link, T1 or other internet connection mechanism. In otherembodiments, the computer system 1700 may have a direct connection tothe Internet 1723. The computer system 1700 may be connected to one ormore other computers such as desktop computer 1729 or laptop computer1733 via the Internet 1723, an intranet 1731, and/or a wireless node1735. In some embodiments, an expansion slot may be included to allow auser to add additional functionality to the computer system 1700.

The computer system 1700 may include an I/O controller providing accessto external communication interfaces such as universal serial bus (USB)connections, serial ports such as RS-232, parallel ports, audio in andaudio out connections, the high performance serial bus IEEE-1394 and/orother communication links. These connections may also have separatecircuitry in some embodiments, or may be connected through a bridge toanother computer communication link provided by the I/O controller. Agraphics controller may also be provided to allow applications runningon the processor 1701 to display information to a user on a displaydevice 1717. The graphics controller may output video through a videoport that may utilize a standard or proprietary format such as an analogvideo graphic array (VGA) connection, a digital video interface (DVI), adigital high definition multimedia interface (HDMI) connection, or anyother video connection. The video connection may connect to displaydevice 1717 to present the video information to the user.

The display 1717 may be any of several types of displays or computermonitors, including a liquid crystal display (LCD), a cathode ray tube(CRT) monitor, on organic light emitting diode (OLED) array, or othertype of display suitable for displaying information for the user. Thedisplay 1717 may include one or more light emitting diode (LED)indicator lights, or other such display devices. Typically, the computersystem 1700 includes one or more user input/output (I/O) devices such asa keyboard or mouse 1713, dedicated or programmable buttons and/or otheruser input devices 1715 for controlling the computer system 1700. Theuser input devices 1715 may include, but not be limited to, atouchscreen, touchpad, joystick, trackball, tablet, or other suchdevice. The user I/O devices 1715 may connect to the computer system1700 using USB interfaces or other connections such as RS-232, PS/2connector or other interfaces. Various embodiments include input devicesconfigured to accept an input from a user and/or provide an output to auser. For example, some embodiments may include a webcam (e.g., connectvia USB), a speakers and/or microphone 1719 (e.g., connected to audiooutput/input connections). The computer system 1700 typically has akeyboard/mouse 1713 or other user input devices 1715, a monitor 1717,and may be configured to include speakers/microphone 1719, and a webcam.These input/output devices may be used in various combinations, orseparately, as means for presenting information to the user and/orreceiving information and other inputs from a user to be used incarrying out various programs and calculations. Speech recognitionsoftware may be used in conjunction with the microphone to receive andinterpret user speech commands.

The computer system 1700 may be suitable for use in identifying criticalweb services and dynamically relocating them to a new server. Forexample, the processor 1701 may be embodied as a microprocessor,microcontroller, DSP, RISC processor, two or more parallel processors,or any other type of processing unit that one of ordinary skill wouldrecognize as being capable of performing or controlling the functions,steps, activities and methods described herein. A processing unit inaccordance with at least one of the various embodiments can operatecomputer software programs stored (embodied) on computer-readable mediumsuch those compatible with the storage drives 1707, the disk drive 1709,or any other type of hard disk drive, floppy disk, flash memory, ram, orother computer readable medium as recognized by those of ordinary skillin the art.

As will be appreciated by those of ordinary skill in the art, aspects ofthe various embodiments may be embodied as systems, methods or computerprogram products. Accordingly, aspects of the present invention may takethe form of one or more entirely hardware embodiments, one or moreentirely method embodiments, one or more entirely software embodiments(including firmware, resident software, micro-code, or the like) or oneor more embodiments combining software, method steps, and/or hardwareaspects that may all generally be referred to herein as a “circuit,”“module,” “logic” or “system.” Furthermore, aspects of the variousembodiments may take the form of a computer program product embodied inone or more computer readable medium(s) having computer readable programcode stored thereon.

Any combination of one or more non-transitory computer readablemedium(s) may be utilized. The computer readable medium is typically acomputer readable storage medium. A computer readable storage medium maybe embodied as, for example, an electronic, magnetic, optical,electromagnetic, infrared, or semiconductor system, apparatus, ordevice, or other like storage devices known to those of ordinary skillin the art, or any suitable combination of the foregoing. A computer, inthis context, may be a general purpose computer (e.g., a laptop ordesktop computer, PDA, or like device), a special purpose computer(e.g., a server computer or like device), or other programmable dataprocessing apparatus (e.g., a microprocessor, machine controller, orlike device). Examples of computer readable storage medium include thefollowing: an electrical connection having one or more wires, a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a portable compact disc read-only memory (CD-ROM), anoptical storage device, a magnetic storage device, or any suitablecombination of the foregoing. In the context of this document, acomputer readable storage medium may be any tangible medium that cancontain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Computer program code for carrying out operations and aspects of thevarious embodiments may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++, or the like, and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. In accordance with various implementations, theprogram code may execute entirely on the user's computer, partly on theuser's computer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Various embodiments of this disclosure include the apparatus and systemsdepicted in the figures and described above as well as method of usingand making the apparatus and systems. Aspects of the various embodimentscan be implemented by computer program instructions. These computerprogram instructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, a programmable dataprocessing apparatus, or other such devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computer, other programmable data processing apparatus, orother devices to cause a series of operational steps to be performed onthe computer, other programmable apparatus or other devices to produce acomputer implemented process such that the instructions which execute onthe computer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and/or block diagrams in the figures help to illustratethe architecture, functionality, and operation of possibleimplementations of systems, methods and computer program productsaccording to various embodiments of the present invention. In thisregard, each block in the flowchart or block diagrams may represent amodule, segment, or portion of code, which comprises one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur in an orderother than that depicted in the figures. For example, two blocks shownin succession may, in fact, be executed substantially concurrently, orthe blocks and activities of the figures may sometimes be executed inreverse order or in a different order, depending upon the functionalityinvolved. It will also be noted that each block of the block diagramsand/or flowchart illustration, and combinations of blocks in the blockdiagrams and/or flowchart illustration, can be implemented by specialpurpose hardware-based systems that perform the specified functions oracts, or combinations of special purpose hardware and computerinstructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including” used in this specificationspecify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. The term “obtaining”, asused herein and in the claims, may mean either retrieving from acomputer readable storage medium, receiving from another computerprogram, receiving from a user, calculating based on other input, or anyother means of obtaining a datum or set of data. The term “plurality”,as used herein and in the claims, means two or more of a named element.It should not, however, be interpreted to necessarily refer to everyinstance of the named element in the entire device. Particularly, ifthere is a reference to “each” element of a “plurality” of elements.There may be additional elements in the entire device that are not beincluded in the “plurality” and are not, therefore, referred to by“each.”

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and gist of the invention. The variousembodiments included herein were chosen and described in order to bestexplain the principles of the invention and the practical application,and to enable others of ordinary skill in the art to understand theinvention for various embodiments with various modifications as aresuited to the particular use contemplated.

What is claimed is:
 1. A negative pressure wound dressing assembly withan inner ventral surface and an outer dorsal surface, the wound dressingassembly comprising: a first netting layer with a ventral side servingas the ventral surface of the wound dressing assembly configured forplacement over a wound; a covering layer with a dorsal side positionedaway from the wound; a second netting layer positioned between the firstnetting layer and the covering layer; a tubing layer positioned betweenthe first netting layer and the second netting layer, the tubing layercomprising a plurality of radially extending tubes positioned between anupper surface of the first netting layer and a lower surface of thesecond netting layer, the plurality of radially extending tubes of thetubing layer extending outwardly from a central connection junctiontoward a periphery of the first and second netting layers and being influidic communication with the central connection junction that isconnectable to one of a source of irrigant and a vacuum source; and avacuum interface chamber for connecting with the vacuum source, thevacuum interface chamber defining an internal space in communicationwith a plurality of openings along a ventral face or a side surfaces ofthe vacuum interface chamber for distributing negative pressure from thevacuum source, wherein the vacuum interface chamber is positioned belowa central region of the covering layer and above the first nettinglayer, the second netting layer, and the tubing layer.
 2. A negativepressure wound dressing assembly with an inner ventral surface and anouter dorsal surface, the wound dressing assembly comprising: a coveringlayer with a dorsal side positioned away from the wound; a vacuuminterface chamber defining an internal space in communication with aplurality of openings along a ventral face or a side surface of thevacuum interface chamber for distributing negative pressure from thevacuum source, wherein the vacuum interface chamber is positioned belowa central region of the covering layer; an irrigation tubing layerpositioned between below the covering layer and below the vacuuminterface chamber, the irrigation tubing layer comprising a plurality ofradially extending irrigation tubes that extend outwardly from a centralconnection junction toward a periphery of the dressing assembly andbeing in fluidic communication with the central connection junction thatis connectable to and irrigation source; and a porous dressing componentdisposed as a ventral surface of the negative pressure wound dressingassembly and positioned below the plurality of radially extendingirrigation tubes of the irrigation tubing layer, the vacuum interfacechamber, and the covering layer, the porous dressing component beingconfigured to cover an open wound.
 3. The negative pressure wounddressing assembly of claim 2, wherein the porous dressing component isnetting of a biologically inert polymer material.
 4. The negativepressure wound dressing assembly of claim 2, wherein the porous dressingcomponent is a perforated film of a biologically inert polymer material.5. The negative pressure wound dressing assembly of claim 2, wherein theporous dressing component is netting impregnated with one or moreantimicrobial agents.
 6. The negative pressure wound dressing assemblyof claim 5, wherein the one or more antimicrobial agents comprisesilver-ions.
 7. The negative pressure wound dressing assembly of claim2, wherein the porous dressing component is netting of a bioabsorbablematerial.
 8. The negative pressure wound dressing assembly of claim 2,wherein the porous dressing component is impregnated with aantimicrobially active agent.
 9. The negative pressure wound dressingassembly of claim 2, wherein the porous dressing component isimpregnated with one or more biologically active agents.
 10. Thenegative pressure wound dressing assembly of claim 2, furthercomprising: a tissue substrate affixed to the porous dressing component.11. The negative pressure wound dressing assembly of claim 2, furthercomprising: radio opaque markers integrated with one or more componentsof the negative pressure wound dressing assembly, the radio opaquemarkers being configured to identify portions of said one or morecomponents retained in the wound following removal of the negativepressure wound dressing assembly.
 12. The negative pressure wounddressing assembly of claim 2, wherein the porous dressing component isnetting covered with a pliable coating material in a manner configuredto reduce fraying of the netting.
 13. The negative pressure wounddressing assembly of claim 2, wherein the porous dressing component hasan abrasive ventral surface configured for debridement of the wound. 14.The negative pressure wound dressing assembly of claim 2, wherein theporous dressing component has a non-stick ventral surface configured toreduce tissue injury upon removal of the porous dressing component fromthe wound.
 15. The negative pressure wound dressing assembly of claim 2,further comprising: one or more ultra-sonic transducers embedded in theporous dressing component and positioned to sit in fluidic communicationwith a surface of the open wound.
 16. The negative pressure wounddressing assembly of claim 2, further comprising a second porousdressing component positioned above the plurality of radially extendingirrigation tubes of the irrigation tubing layer and below the vacuuminterface chamber and the covering layer.
 17. The negative pressurewound dressing assembly of claim 16, wherein both the first and secondporous dressing components comprise a netting layer of a biologicallyinert polymer material.
 18. The negative pressure wound dressingassembly of claim 17, wherein the plurality of radially extendingirrigation tubes of the irrigation tubing layer extend radially outwardin a curved path between an upper surface of the first porous dressingcomponent and a lower surface of the second porous dressing component.19. The negative pressure wound dressing assembly of claim 16, whereinboth the first and second porous dressing components comprise aperforated film layer of a biologically inert polymer material.
 20. Thenegative pressure wound dressing assembly of claim 19, wherein theplurality of radially extending irrigation tubes of the irrigationtubing layer extend radially outward in a curved path between an uppersurface of the first porous dressing component and a lower surface ofthe second porous dressing component.